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Sample records for african dust outbreaks

  1. African dust outbreaks over the Mediterranean Basin during 2001-2011: concentrations, phenomenology and trends

    NASA Astrophysics Data System (ADS)

    Pey, Jorge; Querol, Xavier; Alastuey, Andres; Forastiere, Franceso; Stafoggia, Massimo

    2013-04-01

    Concentrations, phenomenology and trends of African dust outbreaks over the whole Mediterranean Basin werestudied on an 11-year period (2001-2011). This work has been performed in the context of the MED-PARTICLES (LIFE programme, EU) project, devoted to quantify short-term health effects of particulate matter over the Mediterranean region by distinguishing different particle sizes, chemical components and sources, with emphasis in the effects of African dust. In order to evaluate conduct this investigation, PM10 data from 19 regional and suburban background sites West to East in the Mediterranean area were compiled. After identifying the daily occurrence of African dust outbreaks, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sitesacross the Mediterranean, from 30 to 37 % of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25°E westwards across the Basin,is patent across the Mediterranean. From 25°E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodesof dust but also because of inputs from Middle Eastern deserts. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 µg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn

  2. Back-trajectory analysis of African dust outbreaks at a coastal city in southern Spain: Selection of starting heights and assessment of African and concurrent Mediterranean contributions

    NASA Astrophysics Data System (ADS)

    Cabello, M.; Orza, J. A. G.; Dueñas, C.; Liger, E.; Gordo, E.; Cañete, S.

    2016-09-01

    The present study uses a back-trajectory analysis at multiple heights for better interpretation of the impact of the African dust outbreaks in the coastal Mediterranean city of Málaga (Spain), the southernmost large city in Europe. Throughout a 3-year period, 363 days were identified as dusty days by atmospheric transport models. During these events, PM10, SO2, O3, temperature, AOD and Ångström exponent showed statistically significant differences compared to days with no African dust. It was found that under African dust events, the study site was influenced by Mediterranean air masses at the lowermost heights and by Atlantic advections at high altitudes, while African air masses mostly reached Málaga at intermediate levels. Specifically, the lowest heights at which air masses reached the study site after having resided over Africa are confined into the 1000-2000 m range. The decoupling between the lowest heights and the ones for dust transport may explain the presence of aged air masses at the time of the African outbreak. Additionally, with the aim of studying the influence of the air mass origin and history on air quality, a new procedure based on Principal component analysis (PCA) is proposed to determine which altitudes are best suited as starting points for back-trajectory calculations, as they maximize the differences in residence time over different areas. Its application to Málaga identifies three altitudes (750, 2250 and 4500 m) and a subsequent analysis of back-trajectories for African dust days provided the main source areas over Africa as well as further insight on the Mediterranean contribution.

  3. Forecasting the North African dust outbreak towards Europe in April 2011: a model intercomparison

    NASA Astrophysics Data System (ADS)

    Huneeus, N.; Basart, S.; Fiedler, S.; Morcrette, J.-J.; Benedetti, A.; Mulcahy, J.; Terradellas, E.; Pérez García-Pando, C.; Pejanovic, G.; Nickovic, S.; Arsenovic, P.; Schulz, M.; Cuevas, E.; Baldasano, J. M.; Pey, J.; Remy, S.; Cvetkovic, B.

    2015-10-01

    In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models during an intense Saharan dust outbreak affecting Western and Northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead-times of up to 72 h using observations of aerosol optical depth (AOD) from the Aerosol Robotic Network (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS), and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distribution was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead-times. On average, differences among the models are larger than differences among lead-times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards Northern Europe. Our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.

  4. Forecasting the northern African dust outbreak towards Europe in April 2011: A model intercomparison

    DOE PAGESBeta

    Huneeus, N.; Basart, S.; Fiedler, S.; Morcrette, J. -J.; Benedetti, A.; Mulcahy, J.; Terradellas, E.; Garcia-Pando, C. Perez; Pejanovic, G.; Nickovic, S.; et al

    2016-04-21

    In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models during an intense Saharan dust outbreak affecting western and northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead times of up to 72 h using observations of aerosol optical depth (AOD) from the AErosol RObotic NETwork (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distributionmore » was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead times. On average, differences among the models are larger than differences among lead times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards northern Europe. In this paper, our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.« less

  5. Forecasting the northern African dust outbreak towards Europe in April 2011: a model intercomparison

    NASA Astrophysics Data System (ADS)

    Huneeus, N.; Basart, S.; Fiedler, S.; Morcrette, J.-J.; Benedetti, A.; Mulcahy, J.; Terradellas, E.; Pérez García-Pando, C.; Pejanovic, G.; Nickovic, S.; Arsenovic, P.; Schulz, M.; Cuevas, E.; Baldasano, J. M.; Pey, J.; Remy, S.; Cvetkovic, B.

    2016-04-01

    In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models during an intense Saharan dust outbreak affecting western and northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead times of up to 72 h using observations of aerosol optical depth (AOD) from the AErosol RObotic NETwork (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distribution was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead times. On average, differences among the models are larger than differences among lead times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards northern Europe. Our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.

  6. Forecasting the Northern African Dust Outbreak Towards Europe in April 2011: A Model Intercomparison

    NASA Technical Reports Server (NTRS)

    Huneeus, N.; Basart, S.; Fiedler, S.; Morcrette, J.-J.; Benedetti, A.; Mulcahy, J.; Terradellas, E.; Pérez García-Pando, C.; Pejanovic, G.; Nickovic, S.

    2016-01-01

    In the framework of the World Meteorological Organisation's Sand and Dust Storm Warning Advisory and Assessment System, we evaluated the predictions of five state-of-the-art dust forecast models during an intense Saharan dust outbreak affecting western and northern Europe in April 2011. We assessed the capacity of the models to predict the evolution of the dust cloud with lead times of up to 72 hours using observations of aerosol optical depth (AOD) from the AErosol RObotic NETwork (AERONET) and the Moderate Resolution Imaging Spectroradiometer (MODIS) and dust surface concentrations from a ground-based measurement network. In addition, the predicted vertical dust distribution was evaluated with vertical extinction profiles from the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP). To assess the diversity in forecast capability among the models, the analysis was extended to wind field (both surface and profile), synoptic conditions, emissions and deposition fluxes. Models predict the onset and evolution of the AOD for all analysed lead times. On average, differences among the models are larger than differences among lead times for each individual model. In spite of large differences in emission and deposition, the models present comparable skill for AOD. In general, models are better in predicting AOD than near-surface dust concentration over the Iberian Peninsula. Models tend to underestimate the long-range transport towards northern Europe. Our analysis suggests that this is partly due to difficulties in simulating the vertical distribution dust and horizontal wind. Differences in the size distribution and wet scavenging efficiency may also account for model diversity in long-range transport.

  7. African dust outbreaks over the Mediterranean Basin during 2001-2011: PM10 concentrations, phenomenology and trends, and its relation with synoptic and mesoscale meteorology

    NASA Astrophysics Data System (ADS)

    Pey, J.; Querol, X.; Alastuey, A.; Forastiere, F.; Stafoggia, M.

    2013-02-01

    The occurrence of African dust outbreaks over the whole Mediterranean Basin has been studied on an 11-yr period (2001-2011). In order to evaluate the impact of such mineral dust outbreaks on ambient concentrations of particulate matter, PM10 data from regional and suburban background sites across the Mediterranean area were compiled. After identifying the daily influence of African dust, a methodology for the estimation of the natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sites across the Mediterranean, from 30 to 37% of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25° E westwards across the Basin, is patent across the Mediterranean. As a result of this, an experimental equation for the estimation of annual African dust contributions based on the latitudinal position was obtained. From 25° E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodes of dust but also because of inputs from Negev and Middle Eastern deserts. The slightly higher frequency of African dust episodes observed over southern sites in the central Mediterranean Basin is compensated by its moderately lower intensity. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 μg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly

  8. African dust outbreaks over the Mediterranean Basin during 2001-2011: PM10 concentrations, phenomenology and trends, and its relation with synoptic and mesoscale meteorology

    NASA Astrophysics Data System (ADS)

    Pey, J.; Querol, X.; Alastuey, A.; Forastiere, F.; Stafoggia, M.

    2012-10-01

    The occurrence of African dust outbreaks over the whole Mediterranean Basin has been identified on an 11-yr period (2001-2011). In order to evaluate the impact of such mineral dust outbreaks on ambient concentrations of particulate matter, PM10 data from regional and suburban background sites across the Mediterranean area were compiled. After identifying the daily influence of African dust, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our results reveal that African dust outbreaks occur with much higher frequency in southern areas of the Mediterranean, from 30 to 37% of the annual days, whereas they take place less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to equivalent areas in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10 is patent across the Mediterranean. Our study demonstrates that this gradient may be mainly explained by the latitudinal position. A longitudinal increasing trend of African dust contribution to PM10 is also observed from 25° E eastwards, and is due to the annual occurrence of intense dust episodes. Thus, the slightly higher frequency of African dust episodes over the lower part of Central Mediterranean is compensated by its moderately lower intensity. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 μg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn-spring in the eastern side, with yearly occurrence of various severe episodes. Overall, African dust emerges as the largest PM10 source in regional background southern areas of the

  9. Saharan dust outbreaks and iberulite episodes

    NASA Astrophysics Data System (ADS)

    Diaz-Hernandez, Jose L.; Sanchez-Navas, Antonio

    2016-06-01

    Mineral dust aerosols coming from the arid and semiarid regions of the world can aggregate and form microspherulites under special atmospheric conditions. This is the case for iberulites, formed in the atmosphere from Saharan dust intrusions into the southern Iberian Peninsula during the summer, prompting a noteworthy case of dust accretion unique in the world. This study consists of a long-term monitoring of Saharan dust outbreaks producing haze that reaches the southern Iberian Peninsula. Aerosol concentration, relative humidity, and temperature time series available at the ground stations in this area indicate sharp variations of these atmospheric variables during the iberulite-forming events. Most of these events occurred during the summer (60%), with 65 episodes for the period 2005-2013, in which 107 plumes reached the Iberian Peninsula. Iberulite episodes lasted 5 days on average, during which an initial increase of particulate matter (PM) levels and temperature, accompanied by a decrease in relative humidity, was registered until the third day. These trends reversed when the plume began to abate. Our data also indicate that iberulites form during dusty episodes when a minimum threshold in the content of large aerosol particles (PM10) reached concentrations above 15 µg × m-3. Surface evaporation due to the sharply rising air temperatures give rise to clouds associated with the plume, where the water droplets that formed from condensation capture large amounts of aerosols as they fall. In this sense, muddy raindrop impacts with variable water:dust ratios recorded during red-rain episodes are interpreted as the precursor of the iberulites. A singular process of dust aggregation is here proposed for the formation of iberulites.

  10. 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.

  11. A Northward Shift of the North Atlantic Ocean Intertropical Convergence Zone in Response to Summertime Saharan Dust Outbreaks

    NASA Technical Reports Server (NTRS)

    Wilcox, Eric M.; Lau, K. M.; Kim, Kyu-Myong

    2010-01-01

    The influence on the summertime North Atlantic Ocean inter-tropical convergence zone (ITCZ) of Saharan dust outbreaks is explored using nine years of continuous satellite observations and atmospheric reanalysis products. During dust outbreak events rainfall along the ITCZ shifts northward by 1 to 4 degrees latitude. Dust outbreaks coincide with warmer lower-tropospheric temperatures compared to low dust conditions, which is attributable to advection of the warm Saharan Air Layer, enhanced subtropical subsidence, and radiative heating of dust. The enhanced positive meridional temperature gradient coincident with dust outbreaks is accompanied by an acceleration of the easterly winds on the n011h side of the African Easterly Jet (AEJ). The center of the positive vorticity region south of the AEJ moves north drawing the center of low-level convergence and ITCZ rainfall northward with it. The enhanced precipitation on the north side of the ITCZ occurs in spite of widespread sea surface temperature cooling north of the ITCZ owing to reduced surface solar insolation by dust scattering.

  12. The Role of African Easterly Wave on Dust Transport and the Interaction Between Saharan Dust Layer and Atlantic ITCZ During Boreal Summer

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Saharan dust outbreaks not only transport large amount of dust to the northern Atlantic Ocean, but also alter African easterly jet and wave activities along the jet by changing north-south temperature gradient. Recent modeling and observational studies show that during periods of enhance outbreaks, rainfall on the northern part of ITCZ increases in conjunction with a northward shift of ITCZ toward the dust layer. In this paper, we study the radiative forcing of Saharan dust and its interactions with the Atlantic Inter-tropical Convergence Zone (ITCZ), through African easterly waves (AEW), African easterly jet (AEJ), using the Terra/Aqua observations as well as MERRA data. Using band pass filtered EOF analysis, we find that African easterly waves propagating westward along two principal tracks, centered at 15-25N and 5-10N respectively. The easterly waves in the northern track are slower, with propagation speed of 9 ms-1, and highly correlated with major dust outbreak over North Africa. On the other hand, easterly waves along the southern track are faster with propagating speed of 10 ms-1, and are closely tied to rainfall/cloud variations along the Atlantic ITCZ. Dust transport along the southern track leads rainfall/cloud anomalies in the same region by one or two days, suggesting the southern tracks of dust outbreak are regions of strong interaction between Saharan dust layer and Atlantic ITCZ. Possible linkage between two tracks of easterly waves, as well as the long-term change of easterly wave activities and dust outbreaks, are also discussed.

  13. Impact of soil moisture on dust outbreaks in East Asia: Using satellite and assimilation data

    NASA Astrophysics Data System (ADS)

    Kim, Hyunglok; Choi, Minha

    2015-04-01

    This study is the first assessment of the effects of soil moisture on dust outbreaks using satellite-derived aerosol optical depth (AOD) and global assimilation data on the sand regions across East Asia. The relationships among dust outbreaks, soil moisture, and wind speed were estimated using data sets of the Moderate Resolution Imaging Spectroradiometer and Global Land Data Assimilation System collected over 11 years (2003-2013). The mean AOD exponentially decreased with increasing soil moisture under different wind speed conditions (average determination coefficient = 0.95). As the wind speed conditions became stronger, the probability of a dust outbreak became greatly affected by soil moisture. The threshold soil moisture for dust outbreaks increased with increasing wind speed and decreased with increasing dust-outbreak criteria of AOD. Our results have the capability to be applied to satellite-based dust-outbreak prediction and global-scale dust-emission studies.

  14. Iron mobilization in North African dust.

    SciTech Connect

    Ito, A.; Feng, Y.

    2011-01-01

    Iron is an essential nutrient for phytoplankton. Although iron-containing dust mobilized from arid regions supplies the majority of the iron to the oceans, the key flux in terms of the biogeochemical response to atmospheric deposition is the amount of soluble or bioavailable iron. Atmospheric processing of mineral aerosols by anthropogenic pollutants (e.g. sulfuric acid) may transform insoluble iron into soluble forms. Previous studies have suggested higher iron solubility in smaller particles, as they are subject to more thorough atmospheric processing due to a longer residence time than coarse particles. On the other hand, the specific mineralogy of iron in dust may also influence the particulate iron solubility in size. Compared to mineral dust aerosols, iron from combustion sources could be more soluble, and found more frequently in smaller particles. Internal mixing of alkaline dust with iron-containing minerals could significantly reduce iron dissolution in large dust aerosols due to the buffering effect, which may, in contrast, yield higher solubility in smaller particles externally mixed with alkaline dust (Ito and Feng, 2010). Here, we extend the modeling study of Ito and Feng (2010) to investigate atmospheric processing of mineral aerosols from African dust. In contrast to Asian dust, we used a slower dissolution rate for African dust in the fine mode. We compare simulated fractional iron solubility with observations. The inclusion of alkaline compounds in aqueous chemistry substantially limits the iron dissolution during long-range transport to the Atlantic Ocean: only a small fraction of iron (<0.2%) dissolves from illite in coarsemode dust aerosols with 0.45% soluble iron initially. In contrast, a significant fraction (1-1.5%) dissolves in fine-mode dust aerosols due to the acid mobilization of the iron-containing minerals externally mixed with carbonate minerals. Consequently, the model generally reproduces higher iron solubility in smaller particles

  15. African Dust Blows over the Caribbean

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Shuttle astronauts frequently track Saharan dust storms as they blow from north Africa across the Atlantic Ocean. Dust palls blowing from Africa take about a week to cross the Atlantic. Recently, researchers have linked Saharan dust to coral disease, allergic reactions in humans, and red tides. The top photograph, a classic image showing African dust over the Caribbean, was taken at a time when few scientists had considered the possibility. The image was taken by Space Shuttle astronauts on July 11, 1994 (STS065-75-47). This photograph looks southwest over the northern edge of a large trans-Atlantic dust plume that blew off the Sahara desert in Africa. In this view, Caicos Island in the Bahamas and the mountainous spines of Haiti are partly obscured by the dust. Closer to the foreground, (about 26 degrees north latitude), the skies are clear. The lower photograph (STS105-723-7) was taken by Space Shuttle astronauts while docked to the International Space Station on August 19, 2001. The spacecraft is over the Atlantic Ocean at roughly 45oN, 60oW. The astronauts were looking obliquely to the south; the boundaries of the dust plumes can be traced visually by the abrupt change from clear to hazy atmosphere-the hazy line marks the northern edge of the dust pall near the Caribbean. Images provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

  16. 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

  17. Direct Radiative Effect of Intense Dust Outbreaks in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Obiso, V.; Basart, S.; Jorba, O.; Pérez García-Pando, C.; Hatzianastassiou, N.; Gassó, S.; Baldasano, J. M.

    2015-12-01

    The broader Mediterranean basin is affected by intense desert dust outbreaks in spring. In the present study, we make use of satellite observations and modelling to investigate dust radiative impacts during three consecutive dust outbreaks occurred over the Mediterranean in the period 9/4-15/4/2008. The direct radiative effect (DRE) is estimated by using two simulations run with the NMMB/BSC-Dust model, where the interaction between dust aerosols and radiation is activated and deactivated, respectively. The simulation domain covers the North Africa, the Middle East and Europe at 0.25ºx0.25° and 40σ-layers. The first outbreak took place over the central and eastern Mediterranean on the 9th reaching aerosol optical depths (AODs) close to 1. The second one, with AODs up to 2, lasted from 10th to 14th affecting mainly the central Mediterranean. The third one, with AODs up to 5, affected the Iberian Peninsula on the 15th. DREs are computed for the outgoing radiation at the top of the atmosphere (TOA), the absorbed radiation into the atmosphere (ATMAB), for the downwelling (SURF) and the absorbed (NETSURF) radiation at surface, for the shortwave (SW), longwave (LW) and NET (SW+LW) radiation. According to our results, it is evident that DREs' spatial patterns are driven by those of AOD. Negative (cooling) instantaneous DRETOA, DRESURF and DRENETSURF values up to -500W/m2, -700W/m2 and -600W/m2, respectively, and positive (warming) instantaneous DREATMAB up to 340W/m2 are found for the SW spectrum, during daytime. Opposite but less pronounced effects are encountered for the LW radiation and during nightime. Due to these perturbations on the radiation field, the surface temperature is reduced locally by up to 8°C during daytime and increased by up to 4°C during nightime. It is found that the regional average NET DREs can be as large as -12W/m2, -45W/m2, -30W/m2 and 27W/m2 for TOA, SURF, NETSURF and ATMAB, respectively. Impacts on atmospheric stability and dust

  18. Asian Dust Storm Outbreaks: A Satellite-Surface Perspective

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee

    2006-01-01

    Airborne dusts from northern China contribute a significant part of the air quality problem and, to some extent, regional climatic impact in Asia during springtime. Asian dust typically originates in desert areas far from polluted urban regions. During the transport, dust layers can interact with anthropogenic sulfate and soot aerosols from heavily polluted urban areas. Added to the complex effects of clouds and natural marine aerosols, dust particles reaching the marine environment can have drastically different properties than those from the source. Thus, understanding the unique temporal and spatial variations of Asian dust is of special importance in regional-to-global climate issues (e.g., radiative forcing, hydrological cycle, and primary biological productivity in the mid-Pacific Ocean, etc.), as well as societal concerns (e.g., adverse health effects to humans). The Asian dust and air pollution aerosols can be detected by its colored appearance on current Earth observing satellites (e.g., MODIS, SeaWiFS, TOMS, etc.) and its evolution monitored by satellites and surface network (e.g. AERONET, SKY NET, MPLNET, etc.). Recently, many field campaigns (e.g., ACE-Asia-2001, TRACEP-2001, ADE-2002 & -2003, APEX-2001 & -2003, etc.) were designed and executed to study the compelling variability in spatial and temporal scale of both pollution-derived and naturally occurring aerosols, which often exist in high concentrations over eastern Asia and along the rim of the western Pacific. I will present an overview of the outbreak of Asian dust storms from space and surface observations and to address the climatic effects and societal impacts.

  19. Impact of intensive dust outbreaks on marine primary production as seen by satellites

    NASA Astrophysics Data System (ADS)

    Papadimas, Christos; Hatzianastassiou, Nikos; Mihalopoulos, Nikos; Kanakidou, Maria

    2016-04-01

    The impact of intensive dust outbreaks from the African continent on the marine primary production of the Mediterranean sea is here investigated using MODIS satellite observations of atmospheric aerosol optical depth and chlorophyll-a in the seawater. Dust outbreak episodes in the area are detected based on aerosol relevant satellite observations over a 12-year period from 2003 to 2014. For a total of 167 identified episodes, correlations between aerosol optical depth and chlorophyll-a are investigated both on regional and on a pixel by pixel basis as well as for simultaneous or time-lagged satellite observations. The identified co-variations are thoroughly discussed in view of the impact of nutrient atmospheric deposition on the marine biology in the Mediterranean Sea ecosystem. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARISTEIA - PANOPLY (Pollution Alters Natural Aerosol Composition: implications for Ocean Productivity, cLimate and air qualitY) grant.

  20. Does Water Hyacinth on East African Lakes Promote Cholera Outbreaks?

    PubMed Central

    Feikin, Daniel R.; Tabu, Collins W.; Gichuki, John

    2010-01-01

    Cholera outbreaks continue to occur regularly in Africa. Cholera has been associated with proximity to lakes in East Africa, and Vibrio cholerae has been found experimentally to concentrate on the floating aquatic plant, water hyacinth, which is periodically widespread in East African lakes since the late 1980s. From 1994 to 2008, Nyanza Province, which is the Kenyan province bordering Lake Victoria, accounted for a larger proportion of cholera cases than expected by its population size (38.7% of cholera cases versus 15.3% of national population). Yearly water-hyacinth coverage on the Kenyan section of Lake Victoria was positively associated with the number of cholera cases reported in Nyanza Province (r = 0.83; P = 0.0010). Water hyacinth on freshwater lakes might play a role in initiating cholera outbreaks and causing sporadic disease in East Africa. PMID:20682884

  1. Quiescence of Asian dust events in South Korea and Japan during 2012 spring: Dust outbreaks and transports

    NASA Astrophysics Data System (ADS)

    Lee, Yun Gon; Ho, Chang-Hoi; Kim, Joo-Hong; Kim, Jhoon

    2015-08-01

    This study examined the quiescence of Asian dust events in South Korea and Japan during the spring of 2012, presenting a synoptic characterization and suggesting possible causes. Synoptic observation reports from the two countries confirmed that spring 2012 had the lowest number of dust events in 2000-2012. The monthly dust frequency (DF) in March 2012 over the dust source regions, i.e., deserts in northern China and Mongolia, indicated a significant decrease compared to the 12 year (2000-2011) March climatology. The DF in April 2012 was comparable to the 12 year climatology values, but in May 2012 it was slightly lower. The daily Ozone Monitoring Instrument Aerosol Index and the Navy Aerosol Analysis and Prediction System simulations revealed stagnant dust movement in March and May 2012. Anomalous anticyclones north of the source regions decreased the dust outbreaks and enhanced the southeasterly winds, resulting in few dust events over the downwind countries (i.e., South Korea and Japan). By contrast, in April 2012, a strong anomalous cyclone east of Lake Baikal slightly increased the dust outbreaks over northeastern China. However, the major dust outbreaks were not transported downwind because of exceptional dust pathways, i.e., the southeastward pathway of dust transport was unusually blocked by the expansion of an anomalous anticyclonic circulation over the Sea of Okhotsk, with dust being transported northeast.

  2. Dust-rainfall feedbacks in the West African Sahel

    NASA Astrophysics Data System (ADS)

    Hui, Wanching Jacquie; Cook, Benjamin I.; Ravi, Sujith; Fuentes, José D.; D'Odorico, Paolo

    2008-05-01

    Dust aerosols can suppress rainfall by increasing the number of cloud condensation nuclei in warm clouds and affecting the surface radiation budget and boundary layer instability. The extent to which atmospheric dust may affect precipitation yields and the hydrologic cycle in semiarid regions remains poorly understood. We investigate the relationship between dust aerosols and rainfall in the West African Sahel where the dust-rainfall feedback has been speculated to contribute to sustained droughts. We find that the amount of dust loadings is negatively correlated with rainfall values, suggesting that dust entrained in the atmosphere can significantly inhibit rainfall in this region.

  3. The Role of African Easterly Wave on Dust Transport and the Interaction Between Saharan Dust Layer and Atlantic ITCZ During Boreal Summer

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    In this paper, we investigate the relationships among Saharan dust outbreak and transport, African easterly waves (AEW), African easterly jet (AEJ) and associated convective activities of Atlantic Intertropical Convergence Zone (ITCZ) using Cloudsat-Calipso, MODIS and MERRA data. We find that a major Saharan dust outbreak is associated with the formation of a westward propagating strong cyclone around 15-25N over the western part northern Saharan. The strong cyclonic flow mobilizes and lifts the dust from the desert surface to a high elevation. As the cyclone propagate westward, it transports a thick elevated dust layer between 900 -500 hPa from the African continent to the eastern Atlantic. Cloudiness is reduced within the warm, dry dusty layer, but enhanced underneath it, possibly due to the presence of a shallow inversion layer over the marine boundary layer. The dust outbreak is linked to enhanced deep convection in the northern part of Atlantic ITCZ, abutting the southern flank of the dust layer, and a strengthening of the northward flank of the AEJ. As the dust layer spreads westward, it loses elevation and becomes increasing diffused as it reaches the central and western Atlantic. Using band pass filtered EOF analysis of MERRA winds, we find that AEWs propagating westward along two principal tracks, centered at 15-25N and 5-10N respectively. The easterly waves in the northern track are highly correlated with major dust outbreak over North Africa and associated with slower moving systems, with a quasi-periodicity of 6-9 day. On the other hand, easterly waves along the southern track are faster, with quasi-periodicity of 3-5 days. These faster easterly waves are closely tied to rainfall/cloud variations along the Atlantic ITCZ. Dust transport along the southern track by the faster waves generally leads rainfall/cloud anomalies in the same region by one or two days, suggesting the southern tracks of dust outbreak are regions of strong interaction between

  4. 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

  5. Atmospheric microbiology in the northern Caribbean during African dust events

    USGS Publications Warehouse

    Griffin, Dale W.; Kellogg, C.A.; Garrison, V.H.; Lisle, J.T.; Borden, T.C.; Shinn, E.A.

    2003-01-01

    Between July 2000 and August 2001 forty-three air samples were collected in the northern Caribbean: Twenty-six in the US Virgin Islands, and 17 samples aboard ship during two 1-week cruises. Samples were collected during African dust events and non-dust conditions and screened for the presence of culturable bacteria and fungi. A total of 3,652 liters of air were collected during non-dust conditions, with 19 bacteria and 28 fungi being recovered. During dust conditions a total of 2,369 liters of air were screened resulting in the recovery of 171 bacteria and 76 fungi. A statistically significant difference was found between the two data sets. These results support previous African dust research and further demonstrate that dust particles can serve as a vessel for the global dispersion of bacteria and fungi. Dustborne microorganisms may play a significant role in the ecology and health of downwind ecosystems.

  6. Outbreak of Beriberi among African Union Troops in Mogadishu, Somalia

    PubMed Central

    Watson, John T.; El Bushra, Hassan; Lebo, Emmaculate J.; Bwire, Godfrey; Kiyengo, James; Emukule, Gideon; Omballa, Victor; Tole, John; Zuberi, Muvunyi; Breiman, Robert F.; Katz, Mark A.

    2011-01-01

    Context and Objectives In July 2009, WHO and partners were notified of a large outbreak of unknown illness, including deaths, among African Union (AU) soldiers in Mogadishu. Illnesses were characterized by peripheral edema, dyspnea, palpitations, and fever. Our objectives were to determine the cause of the outbreak, and to design and recommend control strategies. Design, Setting, and Participants The illness was defined as acute onset of lower limb edema, with dyspnea, chest pain, palpitations, nausea, vomiting, abdominal pain, or headache. Investigations in Nairobi and Mogadishu included clinical, epidemiologic, environmental, and laboratory studies. A case-control study was performed to identify risk factors for illness. Results From April 26, 2009 to May 1, 2010, 241 AU soldiers had lower limb edema and at least one additional symptom; four patients died. At least 52 soldiers were airlifted to hospitals in Kenya and Uganda. Four of 31 hospitalized patients in Kenya had right-sided heart failure with pulmonary hypertension. Initial laboratory investigations did not reveal hematologic, metabolic, infectious or toxicological abnormalities. Illness was associated with exclusive consumption of food provided to troops (not eating locally acquired foods) and a high level of insecurity (e.g., being exposed to enemy fire on a daily basis). Because the syndrome was clinically compatible with wet beriberi, thiamine was administered to ill soldiers, resulting in rapid and dramatic resolution. Blood samples taken from 16 cases prior to treatment showed increased levels of erythrocyte transketolase activation coefficient, consistent with thiamine deficiency. With mass thiamine supplementation for healthy troops, the number of subsequent beriberi cases decreased with no further deaths reported. Conclusions An outbreak of wet beriberi caused by thiamine deficiency due to restricted diet occurred among soldiers in a modern, well-equipped army. Vigilance to ensure adequate

  7. 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

  8. 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

  9. 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.

  10. The past, present and future of African dust

    NASA Astrophysics Data System (ADS)

    Evan, Amato T.; Flamant, Cyrille; Gaetani, Marco; Guichard, Françoise

    2016-03-01

    African dust emission and transport exhibits variability on diurnal to decadal timescales and is known to influence processes such as Amazon productivity, Atlantic climate modes, regional atmospheric composition and radiative balance and precipitation in the Sahel. To elucidate the role of African dust in the climate system, it is necessary to understand the factors governing its emission and transport. However, African dust is correlated with seemingly disparate atmospheric phenomena, including the El Niño/Southern Oscillation, the North Atlantic Oscillation, the meridional position of the intertropical convergence zone, Sahelian rainfall and surface temperatures over the Sahara Desert, all of which obfuscate the connection between dust and climate. Here we show that the surface wind field responsible for most of the variability in North African dust emission reflects the topography of the Sahara, owing to orographic acceleration of the surface flow. As such, the correlations between dust and various climate phenomena probably arise from the projection of the winds associated with these phenomena onto an orographically controlled pattern of wind variability. A 161-year time series of dust from 1851 to 2011, created by projecting this wind field pattern onto surface winds from a historical reanalysis, suggests that the highest concentrations of dust occurred from the 1910s to the 1940s and the 1970s to the 1980s, and that there have been three periods of persistent anomalously low dust concentrations—in the 1860s, 1950s and 2000s. Projections of the wind pattern onto climate models give a statistically significant downward trend in African dust emission and transport as greenhouse gas concentrations increase over the twenty-first century, potentially associated with a slow-down of the tropical circulation. Such a dust feedback, which is not represented in climate models, may be of benefit to human and ecosystem health in West Africa via improved air quality and

  11. The past, present and future of African dust.

    PubMed

    Evan, Amato T; Flamant, Cyrille; Gaetani, Marco; Guichard, Françoise

    2016-03-24

    African dust emission and transport exhibits variability on diurnal to decadal timescales and is known to influence processes such as Amazon productivity, Atlantic climate modes, regional atmospheric composition and radiative balance and precipitation in the Sahel. To elucidate the role of African dust in the climate system, it is necessary to understand the factors governing its emission and transport. However, African dust is correlated with seemingly disparate atmospheric phenomena, including the El Niño/Southern Oscillation, the North Atlantic Oscillation, the meridional position of the intertropical convergence zone, Sahelian rainfall and surface temperatures over the Sahara Desert, all of which obfuscate the connection between dust and climate. Here we show that the surface wind field responsible for most of the variability in North African dust emission reflects the topography of the Sahara, owing to orographic acceleration of the surface flow. As such, the correlations between dust and various climate phenomena probably arise from the projection of the winds associated with these phenomena onto an orographically controlled pattern of wind variability. A 161-year time series of dust from 1851 to 2011, created by projecting this wind field pattern onto surface winds from a historical reanalysis, suggests that the highest concentrations of dust occurred from the 1910s to the 1940s and the 1970s to the 1980s, and that there have been three periods of persistent anomalously low dust concentrations--in the 1860s, 1950s and 2000s. Projections of the wind pattern onto climate models give a statistically significant downward trend in African dust emission and transport as greenhouse gas concentrations increase over the twenty-first century, potentially associated with a slow-down of the tropical circulation. Such a dust feedback, which is not represented in climate models, may be of benefit to human and ecosystem health in West Africa via improved air quality and

  12. 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.

  13. Dust-rainfall feedback in West African Sahel

    NASA Astrophysics Data System (ADS)

    Yu, Kailiang; D'Odorico, Paolo; Bhattachan, Abinash; Okin, Gregory S.; Evan, Amato T.

    2015-09-01

    Drought persistence in West African Sahel has often been explained as an effect of positive vegetation-atmosphere feedback associated with surface albedo or the partitioning of solar radiation into sensible and latent heat fluxes. An often overlooked aspect of land-atmosphere coupling results from vegetation controls on dust emissions and the ability of mineral aerosols to suppress precipitation. Here we first consider the case of local (endogenous) dynamics within the Sahel, whereby enhanced dust emissions resulting from a decrease in vegetation partly suppress precipitation, thereby further reducing vegetation cover. We then account for teleconnections between Sahel precipitation and exogenous (i.e., Saharan) dust emissions due to an increase in Saharan wind speed in years of above average Sahel precipitation. We find that in both cases vegetation-climate dynamics may have two stable states, one with low precipitation and high concentration of atmospheric dust and the other with high precipitation and lower levels of atmospheric dust.

  14. Impact of the Saharan dust outbreaks on the ambient levels of total suspended particles (TSP) in the marine boundary layer (MBL) of the Subtropical Eastern North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Alonso-Pérez, S.; Cuevas, E.; Querol, X.; Viana, M.; Guerra, J. C.

    Six years (1998-2003) of measurements of ambient air concentrations of total suspended particulate (TSP) measured at a rural background monitoring station in Tenerife (Canary Islands), the El Río station (ER, 28°08'35″N, 16°39'20″W, 500 m a.s.l.) were studied. African dust outbreaks were objectively identified using a new quantitative tool, called the African Index. This index indicates the percentage of time that an air mass remained over an African region at one of three possible height intervals of the lower troposphere. After identifying these episodes, a study of the background TSP levels at the ER station and of direct and indirect (those which cause vertical deposition of dust) African air mass intrusion impacts was performed. Taking into account both direct and indirect episodes, a total of 322 days of African dust intrusion were objectively identified (a mean of 54 episodes per year) in the period 1998-2003, some of them caused by "transition episodes" or "return African air masses". A subjective method confirmed that 256 of these days were caused by direct impacts of African dust on the ER station. A mean TSP value of 21.6 μg m -3 was found at the station during this period. All the episodes occurred when the TSP concentration was >28.5 μg m -3. The TSP background (˜14 μg m -3) can be assumed to be representative of the MBL of the Eastern North Atlantic subtropical region. The highest number of dust gravitational settlement (or indirect) episodes occurs in summer, but the highest contribution of these episodes to the TSP levels is in March with a monthly mean TSP contribution of up to 30.5 μg m -3.

  15. 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

  16. Far-Reaching Impacts of African Dust- A Calipso Perspective

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Prospero, Joseph; Omar, Ali; Remer, Lorraine; Winker, David; Yang, Yuekui; Zhang, Yan; Zhang, Zhibo

    2014-01-01

    African dust can transport across the tropical Atlantic and reach the Amazon basin, exerting far-reaching impacts on climate in downwind regions. The transported dust influences the surface-atmosphere interactions and cloud and precipitation processes through perturbing the surface radiative budget and atmospheric radiative heating and acting as cloud condensation nuclei and ice nuclei. Dust also influences biogeochemical cycle and climate through providing nutrients vital to the productivity of ocean biomass and Amazon forests. Assessing these climate impacts relies on an accurate quantification of dust transport and deposition. Currently model simulations show extremely large diversity, which calls for a need of observational constraints. Kaufman et al. (2005) estimated from MODIS aerosol measurements that about 144 Tg of dust is deposited into the tropical Atlantic and 50 Tg of dust into the Amazon in 2001. This estimated dust import to Amazon is a factor of 3-4 higher than other observations and models. However, several studies have argued that the oversimplified characterization of dust vertical profile in the study would have introduced large uncertainty and very likely a high bias. In this study we quantify the trans-Atlantic dust transport and deposition by using 7 years (2007-2013) observations from CALIPSO lidar. CALIPSO acquires high-resolution aerosol extinction and depolarization profiles in both cloud-free and above-cloud conditions. The unique CALIPSO capability of profiling aerosols above clouds offers an unprecedented opportunity of examining uncertainties associated with the use of MODIS clear-sky data. Dust is separated from other types of aerosols using the depolarization measurements. We estimated that on the basis of 7-year average, 118142 Tg of dust is deposited into the tropical Atlantic and 3860 Tg of dust into the Amazon basin. Substantial interannual variations are observed during the period, with the maximum to minimum ratio of about 1

  17. Following Saharan Dust Outbreak Toward The Amazon Basin

    NASA Astrophysics Data System (ADS)

    Ben Ami, Y.; Koren, I.; Rudich, Y.; Flores, M.

    2008-12-01

    The role of the Amazon rainforest on earth climatic system is well recognized. To keep forest wellbeing and the fragile balance between the rainforest and the atmosphere, the Amazon must contain a satisfactory amount of nutrients to support the plants. The extensive rain and floods wash most of the soluble nutrients from the rainforest soil, leaving behind acidic kaolinite clay or sandy soil, with limited minerals for plant growth. It was suggested that lack of mineral in the soil may be replenished by deposition of Saharan mineral dust. Using remote sensing data (from the A-train satellites constellation) following with in-situ measurements (as part of the AMazonian Aerosol CharacteriZation Experiment (AMZE) campaign), ground-based data (from AErosol RObotic NETwork (AERONET)) and back trajectory calculations, we analyzed Saharan dust transport toward the Amazon basin during the AMZE period (Feb 7 to Mar 14, 2008). Dust mass, sink, vertical distribution and surface wind speeds were analyzed over the Bodele depression (located in Chad), where most of the dust is emitted, along the Atlantic Ocean and near the Brazilian coastline. Using an integrated data analysis approach we followed dust packages from their emission in the Sahara to their sink in the Amazon forest.

  18. High-resolution regional modeling of summertime transport and impact of African dust over the Red Sea and Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Kalenderski, Stoitchko; Stenchikov, Georgiy

    2016-06-01

    Severe dust outbreaks and high dust loading over Eastern Africa and the Red Sea are frequently detected in the summer season. Observations suggest that small-scale dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand these processes, we present here the first high-resolution modeling study of a dust outbreak in June 2012 developed over East Africa, the Red Sea, and the Arabian Peninsula. Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) component, we identified several dust generating dynamical processes that range from convective to synoptic scales, including synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea, most of the dust transport occurs above 2 km height, whereas across the central and southern parts of the sea; dust is mostly transported below 2 km height. Dust is the dominant contributor (87%) to the aerosol optical depth, producing a domain average cooling effect of -12.1 W m-2 at the surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. Both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. Model results compare well with available ground-based and satellite observations but generally underestimate the observed maximum values of aerosol optical depth. The satellite-retrieved mean optical depth at some locations is underestimated by a factor of 2. A sensitive experiment suggests that these large local differences may result from poor characterization of dust emissions in some areas of the modeled domain. In this case study we successfully simulate the major fine-scale dust generating dynamical processes, explicitly resolving convection and haboob formation. The future

  19. Modulation of Saharan dust export by the North African dipole

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Cuevas, E.; Prospero, J. M.; Alastuey, A.; Querol, X.; López-Solano, J.; García, M. I.; Alonso-Pérez, S.

    2015-07-01

    We have studied the relationship between the long-term interannual variability in large-scale meteorology in western North Africa - the largest and most active dust source worldwide - and Saharan dust export in summer, when enhanced dust mobilization in the hyper-arid Sahara results in maximum dust impacts throughout the North Atlantic. We address this issue by analyzing 28 years (1987-2014) of summer averaged dust concentrations at the high-altitude Izaña observatory (~ 2400 m a.s.l.) on Tenerife, and satellite and meteorological reanalysis data. The summer meteorological scenario in North Africa (aloft 850 hPa) is characterized by a high over the the subtropical Sahara and a low over the tropics linked to the monsoon. We measured the variability of this high-low dipole-like pattern in terms of the North African dipole intensity (NAFDI): the difference of geopotential height anomalies averaged over the subtropics (30-32° N, Morocco) and the tropics (10-13° N, Bamako region) close to the Atlantic coast (at 5-8° W). We focused on the 700 hPa standard level due to dust export off the coast of North Africa tending to occur between 1 and 5 km a.s.l. Variability in the NAFDI is associated with displacements of the North African anticyclone over the Sahara and this has implications for wind and dust export. The correlations we found between the 1987-2014 summer mean of NAFDI with dust at Izaña, satellite dust observations and meteorological re-analysis data indicate that increases in the NAFDI (i) result in higher wind speeds at the north of the Inter-Tropical Convergence Zone that are associated with enhanced dust export over the subtropical North Atlantic, (ii) influence the long-term variability of the size distribution of exported dust particles (increasing the load of coarse dust) and (iii) are associated with enhanced rains in the tropical and northern shifts of the tropical rain band that may affect the southern Sahel. Interannual variability in NAFDI is also

  20. African Dust Concentrations in the Caribbean Island of Puerto Rico

    NASA Astrophysics Data System (ADS)

    Mayol-Bracero, O. L.; Morales-Garcia, F.; Santos-Figueroa, G.; Custals, L.; Izaguirre, M.; Prospero, J. M.; McDowell, W. H.

    2015-12-01

    African dust carried to the Tropical Atlantic and Caribbean was measured during the summer months of 2015. Atmospheric particles during dust events were collected at Cape San Juan, Puerto Rico on stacked-filter units and a high-volume sampler for the fine and coarse fractions and on a low-pressure impactor for size-resolved characterization. The filter ash gravimetric method was used to determine bulk dust mass concentrations for the first time in Puerto Rico. The method was validated analyzing same filter portions at CIAM/ACAR University of Puerto Rico and at RSMAS/MAC University of Miami. Filter's extracts were analyzed for ionic species measured by ion chromatography. The water-soluble organic carbon (WSOC) was determined with a total organic carbon (TOC) analyzer. Mineral dust concentrations in Puerto Rico were compared to those reported at Miami during summer periods. Comparison between dust concentration and regional PM10 data and results on size-resolved dust concentration will also be presented.

  1. African dust forms red soils in Bermuda

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Atreyee

    2012-11-01

    In Bermuda, red, iron-rich, clayey soils, called terra rossa, are storehouses of information not only on past local processes that crafted the topography of the island but also on atmospheric circulation patterns that drove global climate during the Quaternary period (roughly 2.5 million years ago). The origin of the terra rossa, however, has remained a mystery for more than a century. On one hand, dissolution features in the carbonate rocks suggest that local material, for example volcanic rocks, could be the source of these red beds. On the other hand, Bermuda is also uniquely located to receive airborne dust from western Africa as well as from loess deposits of the Mississippi valley of the central United States—both of which could also be potential sources of the terra rossa soils in Bermuda.

  2. Effect of atmospheric mixing layer depth variations on urban air quality and daily mortality during Saharan dust outbreaks

    PubMed Central

    Pandolfi, M.; Tobias, A.; Alastuey, A.; Sunyer, J.; Schwartz, J.; Lorente, J.; Pey, J.; Querol, X.

    2016-01-01

    Several epidemiological studies have shown that the outbreaks of Saharan dust over southern European countries can cause negative health effects. The reasons for the increased toxicity of airborne particles during dust storms remain to be understood although the presence of biogenic factors carried by dust particles or the interaction between dust and man-made air pollution have been hypothesized as possible causes. Intriguingly, recent findings have also demonstrated that during Saharan dust outbreaks the local man-made particulates can have stronger effects on health than during days without outbreaks. We show that the thinning of the mixing layer (ML) during Saharan dust outbreaks, systematically described here for the first time, can trigger the observed higher toxicity of ambient local air. The mixing layer height (MLH) progressively reduced with increasing intensity of dust outbreaks thus causing a progressive accumulation of anthropogenic pollutants and favouring the formation of new fine particles or specific relevant species likely from condensation of accumulated gaseous precursors on dust particles surface. Overall, statistically significant associations of MLH with all-cause daily mortality were observed. Moreover, as the MLH reduced, the risk of mortality associated with the same concentration of particulate matter increased due to the observed pollutants accumulation. The association of MLH with daily mortality and the effect of ML thinning on particle toxicity exacerbated when Saharan dust outbreaks occurred suggesting a synergic effect of atmospheric pollutants on health which was amplified during dust outbreaks. Moreover, the results may reflect higher toxicity of primary particles which predominate on low MLH days. PMID:25051327

  3. Mechanisms and Effects of Summertime Transport of African Dust Through the Tokar Mountain Gap to the Red Sea and Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Kalenderski, S.; Stenchikov, G. L.

    2015-12-01

    Very high dust loading over the Red Sea region in summer strongly affects the nutrition balance and thermal and dynamic regimes of the sea. The observations suggest that small-scale local dynamic and orographic effects, from both the Arabian and African sides, strongly contribute to dust plume formation. To better understand and quantify these processes we present here the first high resolution modeling study of the dust outbreak phenomena in June 2012 over East Africa, the Red Sea, and the Arabian Peninsula using the WRF-Chem model. We identified several dust generating dynamical processes that range from convective to synoptic scales, including: synoptic cyclones, nocturnal low-level jets, and cold pools of mesoscale convective systems. The simulations reveal an eastward transport of African dust across the Red Sea. Over the northern part of the Red Sea most of the dust transport occurs beyond 2 km above ground level and is strengthened by a pressure gradient formed by low pressure over the eastern Mediterranean and high pressure over the Arabian Peninsula. Across the central and southern parts of the Red Sea dust is mostly transported below 2 km height. During the study period dust is a dominant contributor (87%) to aerosol optical depth (AOD), producing a domain average cooling effect of -12.1 W m-2 at surface, a warming of 7.1 W m-2 in the atmosphere, and a residual cooling of -4.9 W m-2 at the top of the atmosphere. WRF-Chem simulations demonstrate that both dry and wet deposition processes contribute significantly to dust removal from the atmosphere. During the dust outbreak 49.2 Tg of dust deposits within the calculation domain, which is approximately 90% of the total dust emission of 54.5 Tg. Model results compare well with available ground-based and satellite observations but generally underestimate the observed AOD maximum values.

  4. Detecting and tracking dust outbreaks by using high temporal resolution satellite data

    NASA Astrophysics Data System (ADS)

    Sannazzaro, Filomena; Marchese, Francesco; Filizzola, Carolina; Tramutoli, Valerio; Pergola, Nicola; Mazzeo, Giuseppe; Paciello, Rossana

    2013-04-01

    A dust storm is a meteorological phenomenon generated by the action of wind, mainly in arid and semi-arid regions of the planet, particularly at subtropical latitudes. Dust outbreaks, of which frequency increases from year to year concurrently with climate change and reduction of moisture in the soil, may strongly impact on human activity as well as on environment and climate. Efficient early warning systems are then required to monitor them and to mitigate their effects. Satellite remote sensing thanks to a global coverage, to a high frequency of observation and low costs of data represents an important tool for studying and monitoring dust outbreaks. Several techniques have been then proposed to detect and monitor these phenomena from space, analyzing signal in different bands of the electromagnetic spectrum. In particular, methods based on the reverse absorption behaviour of silicate particles in comparison with ice crystals and water droplets, at 11 and 12 micron wavelengths, have been largely employed for detecting dust, although some important issues both in terms of reliability and sensitivity still remain. In this work, an optimized configuration of an innovative algorithm for dust detection, based on the largely accepted Robust Satellite Techniques (RST) multi-temporal approach, is then presented. This optimized algorithm configuration is tested here on Spinning Enhanced Visible and Infrared Imager (SEVIRI) data, analyzing some important dust events affecting Mediterranean basin in recent years. Results of this study, assessed on the basis of independent satellite-based aerosol products, generated by using the Total Ozone Mapping Spectrometer (TOMS), the Ozone Monitoring Instrument (OMI), and the Moderate Resolution Imaging Spectroradiometer (MODIS) data, show that when the spectral resolution of SEVIRI is properly exploited dust and meteorological clouds may be better discriminated. These results encourage further experimentations of the proposed

  5. Source Characterization of African Dust Using CCSEM Analysis

    NASA Astrophysics Data System (ADS)

    Rogers, R.; Hunt, A.; Oldfield, F.

    2013-12-01

    A preliminary investigation is underway to determine whether African dust is developed through Pedogenic or Aeolian processes. 85 dust samples were taken from the Sahel and Saharan region of Africa and analyzed using computer controlled scanning electron microscopy (CCSEM). Optimized secondary electron detectors (SED) and back-scattered electron detectors (BSED) with adjustable quadrants was used with a light element Peltier-cooled energy dispersive x-ray spectrometer. A variable pressure system was utilized for the analysis of insulating materials, which eliminated the need for special specimen coating to dissipate charge and remove artifacts. Data from these samples are being used to address two primary questions: (1) Can CCSEM technology accurately describe elemental compounds derived from dust samples and therefore derive mineral content and (2) Are African dusts created through Pedogenic or Aeolian processes. The creation of a 19-point elemental classification system was used to separate and analyze each of the 4000 data points that were taken from 85 samples. Initial findings show large amounts of Fe, Si, and Al-rich minerals. The Al-Si-rich minerals show a close correlation in relative elemental amounts. This is to be expected from clay minerals of the pyroxene group. The Fe, Si-rich minerals trend towards an inverse relationship, which is also consistent with iron oxides of the spinel group that generally consist of magnetite. Other elemental constituents within the samples include varying amounts of Ti, Ca, and K. An initial run of samples, 6 Burkina Soils and 6 Burkina Laterites, show a similarity in chemical composition, leading to the hypothesis that the Burkina Soils originated from the Burkina Laterites. As the experiment progresses we expect to see similar Aeolian processes contributing to the mineral content of other surface dusts. Further research on the effects of these wind driven dusts is needed to assess the potential health impacts and

  6. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Waves in Late Summer, 2003-07

    SciTech Connect

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-12-19

    Episodic events of both Saharan dust outbreaks and African easterly waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan air layer on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximumtropical cyclone activity, in years 2003–07. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, mostAEWsintensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. The authors conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  7. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Wave in Late Summer, 2003-2007

    NASA Technical Reports Server (NTRS)

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-01-01

    Episodic events of both Saharan dust outbreaks and African Easterly Waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan Air Layer (SAL) on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting (WRF) model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximum tropical cyclone activity, in years 2003-2007. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, most AEWs intensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. We conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  8. Trends in African dust transport to the Caribbean: African sources, changing climate, and future scenarios

    NASA Astrophysics Data System (ADS)

    Prospero, J. M.

    2012-12-01

    decades population growth and increased land-use are having an impact on soil mobilization. As to the future, the IPCC 2007 multi-model projections of rainfall in Africa show drier conditions in the North but they could not produce a consensus in the SS region. The absence of a clear relationship between dust transport and African-Atlantic climate and the uncertainties in climate projections make it impossible to anticipate how transport to the Caribbean might change in the future.

  9. African horse sickness outbreaks caused by multiple virus types in Ethiopia.

    PubMed

    Aklilu, N; Batten, C; Gelaye, E; Jenberie, S; Ayelet, G; Wilson, A; Belay, A; Asfaw, Y; Oura, C; Maan, S; Bachanek-Bankowska, K; Mertens, P P C

    2014-04-01

    African horse sickness (AHS) is associated with high morbidity and mortality in equids, especially horses. A retrospective analysis was carried out concerning 737 AHS outbreaks that occurred during 2007-2010 in Ethiopia. A total of ten outbreaks were investigated in the study period. All four forms of the disease (pulmonary, cardiac, horse sickness fever and the combined form) were observed, with the cardiac form being the most prevalent. Multiple African horse sickness virus serotypes (AHSV-2, AHSV-4, AHSV-6, AHSV-8 and AHSV-9) were detected by molecular methods (type-specific real-time RT-PCR assays), and fourteen isolates were derived from blood and tissue samples collected during 2009-2010. This is the first report of AHSV-4, AHSV-6 or AHSV-8 in Ethiopia. PMID:23083078

  10. 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.".

  11. Radiative Effects of Saharan Mineral Dust Aerosols on the Structure of African Easterly Waves

    NASA Astrophysics Data System (ADS)

    Bercos-Hickey, E.; Nathan, T. R.; Chen, S. H.

    2014-12-01

    How Saharan mineral dust affects the structure of African easterly waves (AEWs) is an outstanding scientific question. Addressing this question is important because AEWs often serve as precursors to the development of tropical storms off of West Africa. In this study, the Weather Research and Forecasting Dust (WRFD) model is used to examine the radiative effects of Saharan dust on the structure of AEWs that occurred in July 1995. Two numerical experiments are conducted. The first (control) experiment uses the standard WRF model in the absence of dust. The second experiment is identical to the first, but includes the transport and radiative effects of dust. Dust is modeled by 12 continuity equations for dust-sized particles that represent the spectrum of mineral dust in the atmosphere. Analysis and comparison of the no-dust and dust experiments show that Saharan dust significantly affects the structure of AEWs. For example, a spectral density analysis of the AEWs shows that dust causes higher peak power during the 3 to 6 day period at 700mb. For the meridional wind over Dakar in West Africa, the dust causes the power to increase by about 82% and to shift to a lower frequency by about a half day. Covariance plots show spatial shifts, structural changes and magnitude differences in the AEWs between the dust and no dust experiments. Calculations show that the dust causes the maximum in momentum flux to increase by about 4%. The African easterly jet (AEJ) also shows changes between the dust and no dust experiments. Ongoing work includes quantifying the structural changes of AEWs and the AEJ.

  12. Aerosol characteristics and surface radiative forcing components during a dust outbreak in Gwangju, Republic of Korea.

    PubMed

    Ogunjobi, K O; Kim, Y J

    2008-02-01

    Atmospheric surface aerosol radiative forcing (SARF) DeltaF, forcing efficiency DeltaF(e) and fractional forcing efficiency DeltaFF(e) evaluated from cloud-screened narrowband spectral and thermal-offset-corrected radiometric observations during the Asia dust outbreak episodes in Gwangju, Republic of Korea are reported in this study. Columnar aerosol optical properties (aerosol optical depth (AOD), tau (alambda), Angstrom exponent alpha, mass concentration of fine and coarse mode particles) were also reported for the station between January 2000 and May 2001 consisting of 211cloud-free days. Results indicate that majority of the AOD were within the range 0.25-0.45 while some high aerosol events in which AODs > or = 0.6 were observed during the severe dust episodes. For example, AOD increases from annual average value of 0.34 +/- 0.13 at 501 nm to values >0.60 during the major dust events of March 27-30 and April 7-9, 2000, respectively. The alpha (501-870 nm) which is often used as a qualitative indicator of aerosol particle size had values ranging from 0.01 to 1.77. The diurnal forcing efficiency DeltaDF(e) at Gwangju was estimated to be -81.10 +/- 5.14 W m (-2)/tau (501 nm) and -47.09 +/- 2.20 W m (-2)/tau (501 nm) for the total solar broadband and visible band pass, respectively while the fractional diurnal forcing efficiency DeltaFDF(e) were -15.8 +/- 0.64%/tau (501 nm) and -22.87 +/- 1.13%/tau (501 nm) for the same band passes. Analyses of the 5-day air-mass back trajectories were further developed for Gwangju in order to classify the air-mass and types of aerosol reaching the site during the Asia dust episodes. PMID:17458510

  13. Increase in African dust flux at the onset of commercial agriculture in the Sahel region.

    PubMed

    Mulitza, Stefan; Heslop, David; Pittauerova, Daniela; Fischer, Helmut W; Meyer, Inka; Stuut, Jan-Berend; Zabel, Matthias; Mollenhauer, Gesine; Collins, James A; Kuhnert, Henning; Schulz, Michael

    2010-07-01

    The Sahara Desert is the largest source of mineral dust in the world. Emissions of African dust increased sharply in the early 1970s (ref. 2), a change that has been attributed mainly to drought in the Sahara/Sahel region caused by changes in the global distribution of sea surface temperature. The human contribution to land degradation and dust mobilization in this region remains poorly understood, owing to the paucity of data that would allow the identification of long-term trends in desertification. Direct measurements of airborne African dust concentrations only became available in the mid-1960s from a station on Barbados and subsequently from satellite imagery since the late 1970s: they do not cover the onset of commercial agriculture in the Sahel region approximately 170 years ago. Here we construct a 3,200-year record of dust deposition off northwest Africa by investigating the chemistry and grain-size distribution of terrigenous sediments deposited at a marine site located directly under the West African dust plume. With the help of our dust record and a proxy record for West African precipitation we find that, on the century scale, dust deposition is related to precipitation in tropical West Africa until the seventeenth century. At the beginning of the nineteenth century, a sharp increase in dust deposition parallels the advent of commercial agriculture in the Sahel region. Our findings suggest that human-induced dust emissions from the Sahel region have contributed to the atmospheric dust load for about 200 years. PMID:20613839

  14. Multispecies Epidemiologic Surveillance Study after an Outbreak of Yersiniosis at an African Green Monkey Research Facility

    PubMed Central

    Soto, Esteban; Loftis, Amanda; Boruta, Daniel; Rostad, Sara; Beierschmitt, Amy; McCoy, Matthew; Francis, Stewart; Berezowski, John; Illanes, Oscar; Recinos, Diego; Arauz, Maziel; Spencer, Dustine; Fraites, Trellor; Palmour, Roberta

    2015-01-01

    After an outbreak of Yersinia enterocolitica at a NHP research facility, we performed a multispecies investigation of the prevalence of Yersinia spp. in various mammals that resided or foraged on the grounds of the facility, to better understand the epizootiology of yersiniosis. Blood samples and fecal and rectal swabs were obtained from 105 captive African green monkeys (AGM), 12 feral cats, 2 dogs, 20 mice, 12 rats, and 3 mongooses. Total DNA extracted from swab suspensions served as template for the detection of Y. enterocolitica DNA by real-time PCR. Neither Y. enterocolitica organisms nor their DNA were detected from any of these samples. However, Western blotting revealed the presence of Yersinia antibodies in plasma. The AGM samples revealed a seroprevalence of 91% for Yersinia spp. and of 61% for Y. enterocolitica specifically. The AGM that were housed in cages where at least one fatality occurred during the outbreak (clinical group) had similar seroprevalence to that of AGM housed in unaffected cages (nonclinical group). However, the nonclinical group was older than the clinical group. In addition, 25%, 100%, 33%, 10%, and 10% of the sampled local cats, dogs, mongooses, rats, and mice, respectively, were seropositive. The high seroprevalence after this outbreak suggests that Y. enterocolitica was transmitted effectively through the captive AGM population and that age was an important risk factor for disease. Knowledge regarding local environmental sources of Y. enterocolitica and the possible role of wildlife in the maintenance of yersiniosis is necessary to prevent and manage this disease. PMID:26678370

  15. Multispecies Epidemiologic Surveillance Study after an Outbreak of Yersiniosis at an African Green Monkey Research Facility.

    PubMed

    Soto, Esteban; Loftis, Amanda; Boruta, Daniel; Rostad, Sara; Beierschmitt, Amy; McCoy, Matthew; Francis, Stewart; Berezowski, John; Illanes, Oscar; Recinos, Diego; Arauz, Maziel; Spencer, Dustine; Fraites, Trellor; Palmour, Roberta

    2015-12-01

    After an outbreak of Yersinia enterocolitica at a NHP research facility, we performed a multispecies investigation of the prevalence of Yersinia spp. in various mammals that resided or foraged on the grounds of the facility, to better understand the epizootiology of yersiniosis. Blood samples and fecal and rectal swabs were obtained from 105 captive African green monkeys (AGM), 12 feral cats, 2 dogs, 20 mice, 12 rats, and 3 mongooses. Total DNA extracted from swab suspensions served as template for the detection of Y. enterocolitica DNA by real-time PCR. Neither Y. enterocolitica organisms nor their DNA were detected from any of these samples. However, Western blotting revealed the presence of Yersinia antibodies in plasma. The AGM samples revealed a seroprevalence of 91% for Yersinia spp. and of 61% for Y. enterocolitica specifically. The AGM that were housed in cages where at least one fatality occurred during the outbreak (clinical group) had similar seroprevalence to that of AGM housed in unaffected cages (nonclinical group). However, the nonclinical group was older than the clinical group. In addition, 25%, 100%, 33%, 10%, and 10% of the sampled local cats, dogs, mongooses, rats, and mice, respectively, were seropositive. The high seroprevalence after this outbreak suggests that Y. enterocolitica was transmitted effectively through the captive AGM population and that age was an important risk factor for disease. Knowledge regarding local environmental sources of Y. enterocolitica and the possible role of wildlife in the maintenance of yersiniosis is necessary to prevent and manage this disease. PMID:26678370

  16. Inference and forecast of the current west african ebola outbreak in Guinea, sierra leone and liberia.

    PubMed

    Shaman, Jeffrey; Yang, Wan; Kandula, Sasikiran

    2014-01-01

    The current West African Ebola outbreak poses an unprecedented public health challenge for the world at large. The response of the global community to the epidemic, including deployment of nurses, doctors, epidemiologists, beds, supplies and security, is shaped by our understanding of the spatial-temporal extent and progression of the disease. Ongoing evaluation of the epidemiological characteristics and future course of the Ebola outbreak is needed to stay abreast of any changes to its transmission dynamics, as well as the success or failure of intervention efforts. Here we use observations, dynamic modeling and Bayesian inference to generate simulations and weekly forecasts of the outbreaks in Guinea, Liberia and Sierra Leone. Estimates of key epidemiological characteristics over time indicate continued epidemic growth in West Africa, though there is some evidence of slowing growth in Liberia. 6-week forecasts over successive weeks corroborate these findings; forecasts projecting no future change in intervention efficacy have been more accurate for Guinea and Sierra Leone, but have overestimated incidence and mortality for Liberia. PMID:25642378

  17. Identifying African dust sources that contribute to the seasonal cycles of dust transport to the Caribbean Basin and South America.

    NASA Astrophysics Data System (ADS)

    Prospero, J. M.; Ginoux, P. A.; Molinie, J.

    2014-12-01

    Decades of aerosol measurements on Barbados have yielded a detailed picture of African mineral dust transport to the Caribbean Basin that shows a strong seasonal cycle with a maximum in boreal summer and a minimum in winter. Recently Prospero et al. (Global Biogeochemical Cycles, 2014) presented 10 years (2002 - 2011) of aerosol measurements made at Cayenne, French Guiana, along with concurrent dust measurements on Barbados. The Cayenne study, coupled with satellite products and other evidence, shows that during spring African dust is carried to a broad region of northeastern South America in quantities comparable to, or greater than, those measured at Barbados in summer. Various lines of evidence suggest that the sources that impact on Cayenne in spring are mainly in the Sahel region, including the Bodélé Depression. In summer transport to Barbados is believed to be most affected by emissions that lie in more northerly regions. Thus the record of measurements at Cayenne and Barbados provide a data set that could be used to test the ability of dust transport models to replicate the seasonal shift of dust sources and the consequent impact on transport to these two sites. Here we attempt to link the measurements at Cayenne and Barbados to specific source regions using the GFDL global climate model (Donner et al., 2011) which simulates aerosol mass distributions for dust and other aerosol components. Winds are nudged with the NCEP re-analysis as in Li et al. (2008). The model is run repeatedly over the years 1999-2010, activating dust sources in only one North African country in each run (e.g., Mali, Mauritania, Algeria, Niger, etc.). The model accurately depicts the strong seasonal contrast in dust transport to Barbados and Cayenne and shows the changing impact of African sources over the course of the year. In our presentation we will discuss the model results and compare them to the measurements at the receptor sites. It is notable that during the dust seasons at

  18. Establishing a Functional Link Between African Dust and Region-wide Coral Reef Decline

    NASA Astrophysics Data System (ADS)

    Hayes, M. L.; Barber, R. T.

    2003-12-01

    For nearly thirty years, coral reefs in the Western Atlantic and Caribbean basin have experienced historically unprecedented declines. Algal blooms, mass coral bleaching, disease outbreaks and shifts in the dominance of benthic coral-competitors were first documented in the 1970s and have increased in frequency, intensity, variety and range over the past two decades. Recent studies of decreasing coral cover document regional losses averaging nearly 80% over this period. Here, we provide experimental evidence that increased supplies of iron-rich eolian dust from Africa to typically iron-poor marine environments throughout the region could have played a key role in these profound changes. Atmospheric inputs of "new" micronutrients, especially iron, have the potential to overcome limitations to the growth of opportunistic coral-competitors and the virulence of coral pathogens. Microcosm and mesocosm experiments with a putative bacterial pathogen of stony corals, Aurantimonas coralicida, and a temperate stony coral, Oculina arbuscula, provide a means to test the functional relationship between iron availability, microbial growth and coral health. Iron limitation of A. coralicida growth rates is readily induced by the addition of synthetic chelators such as 2,2' Dipyridyl to bacterial cultures at relatively low concentrations (e.g. 10 μ M). This growth limitation is reversed by 100 nM over-enrichments of pure reagent-grade iron as well as iron-rich "synthetic dust" derived from African lake-bed sediments. The Chrome-azurol S assay demonstrates that A. coralicida also synthesizes high-affinity iron-capture mechanisms (i.e. siderophores) that may serve as critical determinants of virulence. Finally, our experimental mesocosms are based on oligotrophic Mediterranean seawater and permit controlled experimentation under relatively low iron ( ˜5 nM) conditions. Using this system, denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified ribosomal DNA

  19. Comparison of the mixing state of long-range transported Asian and African mineral dust

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Elizabeth; Ault, Andrew P.; Zauscher, Melanie D.; Mayol-Bracero, Olga L.; Prather, Kimberly A.

    2015-08-01

    Mineral dust from arid regions represents the second largest global source of aerosols to the atmosphere. Dust strongly impacts the radiative balance of the earth's atmosphere by directly scattering solar radiation and acting as nuclei for the formation of liquid droplets and ice nuclei within clouds. The climate effects of mineral dust aerosols are poorly understood, however, due to their complex chemical and physical properties, which continuously evolve during atmospheric transport. This work focuses on characterizing atmospheric mineral dust from the two largest global dust sources: the Sahara Desert in Africa and the Gobi and Taklamakan Deserts in Asia. Measurements of individual aerosol particle size and chemical mixing state were made at El Yunque National Forest, Puerto Rico, downwind of the Sahara Desert, and Gosan, South Korea, downwind of the Gobi and Taklamakan Deserts. In general, the chemical characterization of the individual dust particles detected at these two sites reflected the dominant mineralogy of the source regions; aluminosilicate-rich dust was more common at El Yunque (∼91% of El Yunque dust particles vs. ∼69% of Gosan dust particles) and calcium-rich dust was more common at Gosan (∼22% of Gosan dust particles vs. ∼2% of El Yunque dust particles). Furthermore, dust particles from Africa and Asia were subjected to different transport conditions and atmospheric processing; African dust showed evidence of cloud processing, while Asian dust was modified via heterogeneous chemistry and direct condensation of secondary species. A larger fraction of dust detected at El Yunque contained the cloud-processing marker oxalate ion compared to dust detected at Gosan (∼20% vs ∼9%). Additionally, nearly 100% of dust detected at Gosan contained nitrate, showing it was aged via heterogeneous reactions with nitric acid, compared to only ∼60% of African dust. Information on the distinct differences in the chemical composition of mineral dust

  20. An outbreak of Yersinia enterocolitica in a captive colony of African green monkeys (Chlorocebus aethiops sabaeus) in the Caribbean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yersinia enterocolitica is a zoonotic gram-negative pathogen that causes mesenteric lymphadenitis, terminal ileitis, acute gastroenteritis, and septicemia in domestic animals and primates. In 2012, 46 captive African green monkeys (Chlorocebus aethiops sabaeus) died during an outbreak of acutely fat...

  1. Derivation of an observation-based map of North African dust emission

    NASA Astrophysics Data System (ADS)

    Evan, Amato T.; Fiedler, Stephanie; Zhao, Chun; Menut, Laurent; Schepanski, Kerstin; Flamant, Cyrille; Doherty, Owen

    2015-03-01

    Changes in the emission, transport and deposition of aeolian dust have profound effects on regional climate, so that characterizing the lifecycle of dust in observations and improving the representation of dust in global climate models is necessary. A fundamental aspect of characterizing the dust cycle is quantifying surface dust fluxes, yet no spatially explicit estimates of this flux exist for the World's major source regions. Here we present a novel technique for creating a map of the annual mean emitted dust flux for North Africa based on retrievals of dust storm frequency from the Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the relationship between dust storm frequency and emitted mass flux derived from the output of five models that simulate dust. Our results suggest that 64 (±16)% of all dust emitted from North Africa is from the Bodélé depression, and that 13 (±3)% of the North African dust flux is from a depression lying in the lee of the Aïr and Hoggar Mountains, making this area the second most important region of emission within North Africa.

  2. Derivation of an observation-based map of North African dust emission

    SciTech Connect

    Evan, Amato T.; Fiedler, Stephanie; Zhao, Chun; Menut, Laurent; Schepanski, Kerstin; Flamant, C.; Doherty, Owen

    2015-03-01

    Changes in the emission, transport and deposition of aeolian dust have profound effects on regional climate, so that characterizing the lifecycle of dust in observations and improving the representation of dust in global climate models is necessary. A fundamental aspect of characterizing the dust cycle is quantifying surface dust fluxes, yet no spatially explicit estimates of this flux exist for the World’s major source regions. Here we present a novel technique for creating a map of the annual mean emitted dust flux for North Africa based on retrievals of dust storm frequency from the Meteosat Second Generation Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and the relationship between dust storm frequency and emitted mass flux derived from the output of five models that simulate dust. Our results suggest that 64 (±16)% of all dust emitted from North Africa is from the Bodélé depression, and that 13 (±3)% of the North African dust flux is from a depression lying in the lee of the Aïr and Hoggar Mountains, making this area the second most important region of emission within North Africa.

  3. Diagnosis and genotyping of African swine fever viruses from 2015 outbreaks in Zambia.

    PubMed

    Thoromo, Jonas; Simulundu, Edgar; Chambaro, Herman M; Mataa, Liywalii; Lubaba, Caesar H; Pandey, Girja S; Takada, Ayato; Misinzo, Gerald; Mweene, Aaron S

    2016-01-01

    In early 2015, a highly fatal haemorrhagic disease of domestic pigs resembling African swine fever (ASF) occurred in North Western, Copperbelt, and Lusaka provinces of Zambia. Molecular diagnosis by polymerase chain reaction targeting specific amplification of p72 (B646L) gene of ASF virus (ASFV) was conducted. Fourteen out of 16 domestic pigs from the affected provinces were found to be positive for ASFV. Phylogenetic analyses based on part of the p72 and the complete p54 (E183L) genes revealed that all the ASFVs detected belonged to genotypes I and Id, respectively. Additionally, epidemiological data suggest that the same ASFV spread from Lusaka to other provinces possibly through uncontrolled and/or illegal pig movements. Although the origin of the ASFV that caused outbreaks in domestic pigs in Zambia could not be ascertained, it appears likely that the virus may have emerged from within the country or region, probably from a sylvatic cycle. It is recommended that surveillance of ASF, strict biosecurity, and quarantine measures be imposed in order to prevent further spread and emergence of new ASF outbreaks in Zambia. PMID:27247062

  4. African dust carries microbes across the ocean: are they affecting human and ecosystem health?

    USGS Publications Warehouse

    Kellogg, Christina A.; Griffin, Dale W.

    2003-01-01

    Atmospheric transport of dust from northwest Africa to the western Atlantic Ocean region may be responsible for a number of environmental hazards, including the demise of Caribbean corals; red tides; amphibian diseases; increased occurrence of asthma in humans; and oxygen depletion (eutrophication) in estuaries. Studies of satellite images suggest that hundreds of millions of tons of dust are trans-ported annually at relatively low altitudes across the Atlantic Ocean to the Caribbean Sea and southeastern United States. The dust emanates from the expanding Sahara/Sahel desert region in Africa and carries a wide variety of bacteria and fungi. The U.S. Geological Survey, in collaboration with the NASA/Goddard Spaceflight Center, is conducting a study to identify microbes--bacteria, fungi, viruses--transported across the Atlantic in African soil dust. Each year, millions of tons of desert dust blow off the west African coast and ride the trade winds across the ocean, affecting the entire Caribbean basin, as well as the southeastern United States. Of the dust reaching the U.S., Florida receives about 50 percent, while the rest may range as far north as Maine or as far west as Colorado. The dust storms can be tracked by satellite and take about one week to cross the Atlantic.

  5. African dust and the demise of Caribbean Coral Reefs

    NASA Astrophysics Data System (ADS)

    Shinn, Eugene A.; Smith, Garriet W.; Prospero, Joseph M.; Betzer, Peter; Hayes, Marshall L.; Garrison, Virginia; Barber, Richard T.

    2000-10-01

    The vitality of Caribbean coral reefs has undergone a continual state of decline since the late 1970s, a period of time coincidental with large increases in transatlantic dust transport. It is proposed that the hundreds of millions of tons/year of soil dust that have been crossing the Atlantic during the last 25 years could be a significant contributor to coral reef decline and may be affecting other ecosystems. Benchmark events, such as near synchronous Caribbean-wide mortalities of acroporid corals and the urchin Diadema in 1983, and coral bleaching beginning in 1987, correlate with the years of maximum dust flux into the Caribbean. Besides crustal elements, in particular Fe, Si, and aluminosilicate clays, the dust can serve as a substrate for numerous species of viable spores, especially the soil fungus Aspergillus. Aspergillus sydowii, the cause of an ongoing Caribbean-wide seafan disease, has been cultured from Caribbean air samples and used to inoculate sea fans.

  6. African dust and the demise of Caribbean coral reefs

    USGS Publications Warehouse

    Shinn, E.A.; Smith, G.W.; Prospero, J.M.; Betzer, P.; Hayes, M.L.; Garrison, V.; Barber, R.T.

    2000-01-01

    The vitality of Caribbean coral reefs has undergone a continual state of decline since the late 1970s, a period of time coincidental with large increases in transatlantic dust transport. It is proposed that the hundreds of millions of tons/year of soil dust that have been crossing the Atlantic during the last 25 years could be a significant contributor to coral reef decline and may be affecting other ecosystems. Benchmark events, such as near synchronous Caribbean-wide mortalities of acroporid corals and the urchin Diadema in 1983, and coral bleaching beginning in 1987, correlate with the years of maximum dust flux into the Caribbean. Besides crustal elements, in particular Fe, Si, and aluminosilicate clays, the dust can serve as a substrate for numerous species of viable spores, especially the soil fungus Aspergillus. Aspergillus sydowii, the cause of an ongoing Caribbean-wide seafan disease, has been cultured from Caribbean air samples and used to inoculate sea fans.

  7. Evaluation of coral pathogen growth rates after exposure to atmospheric African dust samples

    USGS Publications Warehouse

    Lisle, John T.; Garrison, Virginia H.; Gray, Michael A.

    2014-01-01

    Laboratory experiments were conducted to assess if exposure to atmospheric African dust stimulates or inhibits the growth of four putative bacterial coral pathogens. Atmospheric dust was collected from a dust-source region (Mali, West Africa) and from Saharan Air Layer masses over downwind sites in the Caribbean [Trinidad and Tobago and St. Croix, U.S. Virgin Islands (USVI)]. Extracts of dust samples were used to dose laboratory-grown cultures of four putative coral pathogens: Aurantimonas coralicida (white plague type II), Serratia marcescens (white pox), Vibrio coralliilyticus, and V. shiloi (bacteria-induced bleaching). Growth of A. coralicida and V. shiloi was slightly stimulated by dust extracts from Mali and USVI, respectively, but unaffected by extracts from the other dust sources. Lag time to the start of log-growth phase was significantly shortened for A. coralicida when dosed with dust extracts from Mali and USVI. Growth of S. marcescens and V. coralliilyticus was neither stimulated nor inhibited by any of the dust extracts. This study demonstrates that constituents from atmospheric dust can alter growth of recognized coral disease pathogens under laboratory conditions.

  8. Bulk composition of northern African dust and its source sediments — A compilation

    NASA Astrophysics Data System (ADS)

    Scheuvens, Dirk; Schütz, Lothar; Kandler, Konrad; Ebert, Martin; Weinbruch, Stephan

    2013-01-01

    This paper presents a review of bulk compositional data of northern African dust and its potential source sediments and includes elemental, isotope and mineralogical data. Northern African dust represents about one half of the total global atmospheric mineral dust burden, and its uplift, transport and deposition have strong impacts on climate and various terrestrial and marine ecosystems. The chemical data set shows, that an 'average northern African dust' exhibits comparable Si, Fe and Mn contents with respect to the average composition of the upper continental crust, is slightly depleted in the alkali metals K and Na, and enriched in Ti and P. However, the complete data set yields clear evidence that northern African dust and its source sediments are compositionally heterogeneous on a regional scale and that this heterogeneity can be used to differentiate between major potential source areas on the basis of so-called source markers. An evaluation of these compositional fingerprints shows that the following parameters and especially their combination are effective in the discrimination of the most active source areas in northern Africa: ratio of (Ca + Mg)/Fe [wt.%], calcite (or carbonate) content, palygorskite occurrence and abundance, illite/kaolinite ratio, ?Nd(0) value, and 87Sr/86Sr ratio. For example, the data set corroborates previous ideas, which assign carbonate-, illite- and palygorskite-rich mineral dusts to north(west)ern source regions. Because most of the above listed source markers do not change substantially during transport, even far-traveled dusts may be assigned to specific potential source areas in northern Africa. Some limitations of the presented data set are also discussed. Our compilation reveals some substantial gaps in the knowledge of the composition of source sediments and mineral dusts from important potential source areas that should be filled in the future. The here compiled data set can be used as a reference frame, when

  9. The relationship between gorgonian coral (Cnidaria: Gorgonacea) diseases and African dust storms

    USGS Publications Warehouse

    Weir-Brush, J. R.; Garrison, V.H.; Smith, G.W.; Shinn, E.A.

    2004-01-01

    The number of reports of coral diseases has increased throughout the world in the last 20 years. Aspergillosis, which primarily affects Gorgonia ventalina and G. flabellum, is one of the few diseases to be characterized. This disease is caused by Aspergillus sydowii, a terrestrial fungus with a worldwide distribution. Upon infection, colonies may lose tissue, and ultimately, mortality may occur if the infection is not sequestered. The spores of A. sydowii are <5 ??m, small enough to be easily picked up by winds and dispersed over great distances. Aspergillosis is prevalent in the Caribbean, and it appears that this primarily terrestrial fungus has adapted to a marine environment. It has been proposed that dust storms originating in Africa may be one way in which potential coral pathogens are distributed and deposited into the marine environments of the Caribbean. To test the hypothesis that African dust storms transport and deposit pathogens, we collected air samples from both dust storms and periods of nondust in St. John, U.S. Virgin Islands. Because we focused on fungal pathogens and used A. sydowii as a model, we isolated and cultured fungi on various types of media. Fungi including Aspergillus spp. were isolated from air samples taken from dust events and non-dust events. Twenty-three separate cultures and seven genera were isolated from dust event samples whereas eight cultures from five genera were isolated from non-dust air samples. Three isolates from the Virgin Islands dust event samples morphologically identified as Aspergillus spp. produced signs of aspergillosis in seafans, and the original pathogens were re-isolated from those diseased seafans fulfilling Koch's Postulates. This research supports the hypothesis that African dust storms transport across the Atlantic Ocean and deposit potential coral pathogens in the Caribbean.

  10. 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.

  11. Observation of a Saharan dust outbreaks in the frame of the Convective and Orographically-induced Precipitation Study

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Paolo; Summa, Donato; Bhawar, Rohini; Di Iorio, Tatiana; Caccaini, Marco; Veselovskii, Igor; Kolgotin, Alexey

    2009-03-01

    The Raman lidar system BASIL was operational in Achern (Supersite R, Lat: 48.64° N, Long: 8.06° E, Elev.: 140 m) in the frame of the Convective and Orographically-induced Precipitation Study. BASIL operated continuously over a period of approx. 36 hours from 06:22 UTC on 1 August to 18:28 UTC on 2 August 2007, to cover IOPs 13 a-b. In this timeframe the signature of a severe Saharan dust outbreak episode was captured. An inversion algorithm was used to retrieve particle size distribution parameters, i.e., mean and effective radius, number, surface area, and volume concentration, and complex refractive index, as well as the parameters of a bimodal particle size distribution, from the multi-wavelength lidar data of particle backscattering and extinction. The inversion method employs Tikhonov's inversion with regularization. Size distribution parameters are estimated as a function of altitude at different times during the dust outbreak event. Retrieval results reveal the dominance in the upper dust layer of a coarse mode with radii 3-4 μm. Number density and volume concentration are in the range 100-800 cm-3 and 5-40 μm3/cm3, respectively, while real and imaginary part of the complex refractive index are in the range 1.41-1.53 and 0.003-0.014, respectively.

  12. Mineral dust influence on West-African Sahel rainrates as observed by MODIS and TRMM

    NASA Astrophysics Data System (ADS)

    Klüser, L.; Holzer-Popp, T.

    2009-04-01

    Mineral Dust in the West-African Sahel, either advected from source regions in the Sahara or mobilised by local sources, interacts with the local climate system by modulating the radiation balance and also by changing cloud properties and rainfall. Mineral dust affects rain rates and precipitation amounts of clouds subject to the dust entrainment mainly by the increased number of available cloud condensation nuclei leading to a larger number of cloud droplets with overall smaller droplet sizes. Aerosol observations from the MODerate resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite and rainfall data from the Tropical Rainfall measuring Mission (TRMM) are used to examine the interactions of mineral dust and rainfall in the West-African Sahel. Five years of daily TRMM rainrates and droplet sizes are analysed with respect to atmospheric dust loadings in the West-African Sahel as inferred from MODIS AOD observations (only AOD observations showing mineral dust aerosol as inferred from MODIS aerosol type classification and Ångstrom exponents are used). The ratio of observed precipitation event numbers and total cloud observation numbers in the Sahel is significantly reduced in the presence of mineral dust, reaching up to rainfall reduction by more than 50% in scenes with high dust loading. Not only the number of precipitation events but also the rain rates and raindrop sizes for precipitating clouds are found to be generally reduced under dusty conditions. As well median rain rates as also the spread of the 25%- and 75%-quantiles of the observed rain rate distribution are significantly lower under dusty conditions. From these results it can be concluded that also year-to-year variations of monsoon onset and overall precipitation amount of the summer monsoon, an important factor for both, vegetation and human life in the region, are sensitive to mineral dust export from the Sahara towards the Sahel and to the amount of locally mobilised mineral dust

  13. Long-range transport across the Atlantic in summertime does not enhance the hygroscopicity of African mineral dust

    NASA Astrophysics Data System (ADS)

    Denjean, C.; Caquineau, S.; Desboeufs, K.; Laurent, B.; Maille, M.; Quiñones Rosado, M.; Vallejo, P.; Mayol-Bracero, O. L.; Formenti, P.

    2015-09-01

    We present the first direct evidence that the hygroscopic properties of super micron (>1 µm) African dust particles did not change despite undergoing long-range transport across the Atlantic toward the Caribbean. Concurrent measurements of chemical composition show that most of mineral dust was chemically unprocessed and externally mixed. A minor portion of mineral dust was internally mixed with sulfate and chloride (~13-24% by number) or aggregated with sea-salt particles (~3-6%). Only dust particles aggregated with sea salt showed significant hygroscopic growth above 75% relative humidity (RH), resulting in a decrease in extinction mass efficiency by up to a factor 2.2. All other dust particles did not take up significant amounts of water when exposed to up to 94% RH. These results demonstrate that the direct radiative effect of African dust in this region remained independent of RH and an external mixing state could be considered for evaluating the climate effects of dust.

  14. Raman lidar observations of a Saharan dust outbreak event: Characterization of the dust optical properties and determination of particle size and microphysical parameters

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Paolo; Summa, Donato; Bhawar, Rohini; Di Iorio, Tatiana; Cacciani, Marco; Veselovskii, Igor; Dubovik, Oleg; Kolgotin, Alexey

    2012-04-01

    The Raman lidar system BASIL was operational in Achern (Black Forest) between 25 May and 30 August 2007 in the framework of the Convective and Orographically-induced Precipitation Study (COPS). The system performed continuous measurements over a period of approx. 36 h from 06:22 UTC on 1 August to 18:28 UTC on 2 August 2007, capturing the signature of a severe Saharan dust outbreak episode. The data clearly reveal the presence of two almost separate aerosol layers: a lower layer located between 1.5 and 3.5 km above ground level (a.g.l.) and an upper layer extending between 3.0 and 6.0 km a.g.l. The time evolution of the dust cloud is illustrated and discussed in the paper in terms of several optical parameters (particle backscatter ratio at 532 and 1064 nm, the colour ratio and the backscatter Angström parameter). An inversion algorithm was used to retrieve particle size and microphysical parameters, i.e., mean and effective radius, number, surface area, volume concentration, and complex refractive index, as well as the parameters of a bimodal particle size distribution (PSD), from the multi-wavelength lidar data of particle backscattering, extinction and depolarization. The retrieval scheme employs Tikhonov's inversion with regularization and makes use of kernel functions for randomly oriented spheroids. Size and microphysical parameters of dust particles are estimated as a function of altitude at different times during the dust outbreak event. Retrieval results reveal the presence of a fine mode with radii of 0.1-0.2 μm and a coarse mode with radii of 3-5 μm both in the lower and upper dust layers, and the dominance in the upper dust layer of a coarse mode with radii of 4-5 μm. Effective radius varies with altitude in the range 0.1-1.5 μm, while volume concentration is found to not exceed 92 μm3 cm-3. The real and imaginary part of the complex refractive index vary in the range 1.4-1.6 and 0.004-0.008, respectively.

  15. The Impact of African Dust on PM10 Air Quality in the Caribbean Basin

    NASA Astrophysics Data System (ADS)

    Prospero, J. M.

    2015-12-01

    Decades of aerosol measurements on Barbados and Miami have yielded a broad picture of African mineral dust transport to the Caribbean Basin. These measurements show that in summer the aerosol mass is often dominated by dust. At such times over 90% of the dust mass is comprised of particles less than 10 μm aerodynamic diameter and thus fits the EPA criteria for PM10. A number of sites in the Caribbean monitor PM10 using the same instrumentation commonly deployed in European and United States networks. By comparing data from individual islands that have multiple monitoring sites (e.g., Puerto Rico, Martinique, Guadeloupe), it is shown that during dust events PM10 concentrations track very closely and that local sources have a minor impact on PM10 above about 15 to 20 μg m-3. Moreover the PM10 measurements are coherent with the movement of dust clouds over the islands as observed by satellites. In this way dust movement can be tracked at PM10 sites along the Gulf and southeast coasts of the United States. To assess the specific impact of African dust on PM10 in the region, I compare the daily records of dust measurements at Miami and Barbados with concurrent measurements made at proximate PM10 sites. I then use these relationships and the long term dust measurements at Barbados and Miami to assess the long-term variability of PM10 across the region. At Barbados the record goes back 50 years and provides a basis of assessing the effects of climate variability on PM10 transport. This study shows that there is great variability on scales ranging from daily to decadal. The impact of the droughts in the 1970s and 1980s was particularly significant. Across the Caribbean, the rates of exceedances of the WHO PM10 guideline is comparable to those observed in many major urban areas in Europe and the US. The dominance of dust in large PM10 events and the absence of major pollution sources on many islands offers the opportunity to study the health impacts of desert dust in

  16. A critical evaluation of the ability of SEVIRI thermal IR RGB rendering to identify mineral dust outbreaks

    NASA Astrophysics Data System (ADS)

    Brindley, H.

    2011-12-01

    Imagery derived from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard the Meteosat Second Generation series of geostationary satellites is routinely exploited for a wide variety of forecasting and hazard monitoring applications. By selectively combining the information from different wavelength channels, red-green-blue (RGB) composites can be produced which offer the potential to identify specific features, while the high temporal resolution of SEVIRI allows these features to be tracked forwards or backwards in time. Amongst the various rendering schemes is one designed to identify and monitor desert dust events using the information content within three thermal IR channels. Imagery produced using this rendering has been widely used by the scientific community as a tool to: identify dust sources and activation; assist with field campaign planning, including aircraft in-flight routing; as a visual tool to probe particular dust generation mechanisms and transport; and to qualitatively assess dust forecast model performance. Since the SEVIRI field of view extends across approximately 70°N to 70°S and 70°E to 70°W the instrument is ideally placed to monitor events originating from both African and Arabian dust sources. Nevertheless, interpretation of the imagery is subjective, and the rendering may fail to produce an unambiguous dust signal under certain conditions. Particular candidates which may confound the identification of a dust signature include high levels of atmospheric water vapour, a strong near-surface temperature inversion, the height of the dust layer, the characteristics of the underlying surface, variability in the dust mineralogical composition and in the size of the dust particles. In this paper a quantitative analysis of the ability of the SEVIRI dust RGB imagery to identify dust presence will be presented. This work is partly motivated by the findings of previous studies, but also by ongoing projects such as the UK-led Fennec

  17. Aerosol Physical, Optical and Chemical Properties during African Dust Events at Cape San Juan (CPR)

    NASA Astrophysics Data System (ADS)

    Reyes de Jongh, C.; Mayol Bracero, O. L.; Rivera Vazquez, H.; Sheridan, P.; Ogren, J. A.

    2008-12-01

    Large amounts of atmospheric dust are lifted from the North African deserts and are transported by the trade winds over the Caribbean region, especially during the summer months. How African dust particles influence the earth's radiative budget is not well understood because these particles are highly variable and their physical, optical, and chemical properties are poorly characterized, especially when they are atmospherically processed as are those that travel from Africa to the Caribbean region. Here we present results of aerosol measurements performed at Cape San Juan (CPR), a ground-based station located at the northeastern tip of the Caribbean island of Puerto Rico. We used a condensation particle counter to determine the particle number concentration, a sunphotometer (part of the AErosol RObotical NETwork, AERONET, aeronet.gsfc.nasa.gov) to determine volume size distributions and aerosol optical thickness, and a 3-wavelength nephelometer and particle/soot absorption photometer to determine the scattering and absorption coefficients. Filter samples for chemical analyses were collected with stacked-filter units. Preliminary results show that African dust air masses have higher average particle number concentrations (N=720 cm -3 ), aerosol optical depth (AOD = 0.27), and scattering and absorption coefficients (σ s = 30 Mm -1 , σ a = 0.46 Mm -1 ) than clean air masses (N = 460 cm -3 , AOD= 0.08, σ s = 11 Mm -1 , σ a = 0.37 Mm -1 . Results presented will also show how changes in aerosol optical properties in the presence and absence of African dust relate to the physical and chemical composition of the particles.

  18. Modelling direct radiative effect of mineral dust with the NMMB/BSC-CTM for dust outbreak events over the Mediterranean in summer 2012

    NASA Astrophysics Data System (ADS)

    Obiso, Vincezo; Jorba, Oriol; Basart, Sara; Baldasano, Jose M.; Nabat, Pierre

    2014-05-01

    Aerosols interact with the atmospheric system scattering and absorbing solar radiation, with a significant impact on atmospheric energy and hydrologic processes. Radiative forcing associated with these perturbations affects climate and meteorology. In this contribution, we analyse model results of the Direct Radiative Effect (DRE) of mineral dust over the western-Mediterranean during summer 2012. For that, the NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) is applied on a regional domain at 0.1º horizontal resolution. The NMMB/BSC-CTM is a new on-line chemical weather prediction system coupling atmospheric and chemistry processes. In the radiation module of the model mineral dust is treated as a radiatively active substance interacting both short and longwave radiation. The impact of the mineral dust outbreaks on meteorology is discussed by comparing model forecasts with atmospheric analysis and meteorological observations. The analysis focuses in the vertical structure of the atmosphere and the resulting surface meteorological conditions. The authors acknowledge the support from the grant SEV-2011-00067 of Severo Ochoa Program, awarded by the Spanish Government.

  19. How important are atmospheric depressions and nocturnal low-level jets for North African dust emission?

    NASA Astrophysics Data System (ADS)

    Fiedler, Stephanie; Schepanski, Kerstin; Knippertz, Peter; Heinold, Bernd; Tegen, Ina

    2014-05-01

    margins of the Saharan heat low in summer, have frequencies of up to 80 %. The NLLJ contribution to the dust emission amount is 15 % annually and spatially averaged. Specific regions and seasons show NLLJ contributions of up to 60 %. The largest dust emission associated with NLLJs is found during the mid-morning when the surface inversion decays. In conclusion, atmospheric depressions, migrating cyclones and NLLJs are important for North African dust emission. This climatology enables a process-based evaluation of meteorological drivers of dust emission in atmospheric models that contributes to reducing uncertainty.

  20. An outbreak of encephalomyocarditis-virus infection in free-ranging African elephants in the Kruger National Park.

    PubMed

    Grobler, D G; Raath, J P; Braack, L E; Keet, D F; Gerdes, G H; Barnard, B J; Kriek, N P; Jardine, J; Swanepoel, R

    1995-06-01

    A cluster of four deaths in late December 1993, marked the onset of an outbreak of disease of African elephants (Loxodonta africana) in the Kruger National Park (KNP) in South Africa, which has an estimated population of 7,500 elephants. Mortalities peaked in January 1994, with 32 deaths, and then declined steadily to reach pre-outbreak levels by September, but sporadic losses continued until November. During the outbreak altogether 64 elephants died, of which 53 (83%) were adult bulls. Archival records revealed that, in addition to the usual losses from known causes such as poaching and intraspecific fighting, sporadic deaths from unexplained causes had, in fact, occurred in widely scattered locations from at least 1987 onwards, and from that time until the perceived outbreak of disease there had been 48 such deaths involving 33 (69%) adult bulls. Carcases had frequently become decomposed or had been scavenged by the time they were found, but seven of eight elephants examined early in 1994 had lesions of cardiac failure suggestive of encephalomyocarditis (EMC)-virus infection, and the virus was isolated from the heart muscles of three fresh carcases. The results of tests for neutralizing antibody on 362 elephant sera collected for unrelated purposes from 1984 onwards and kept frozen, indicated that the virus had been present in the KNP since at least 1987. Antibody prevalences of 62 of 116 (53%) 18 of 139 (13%) and seven of 33 (21%) were found in elephants in three different regions of the KNP in 1993 and 1994. Studies had been conducted on myomorph rodents in the KNP for unrelated purposes since 1984, and trapping attempts were increased during the perceived outbreak of disease in elephants. There was a striking temporal correlation between the occurrence of a population explosion (as evidenced by markedly increased catch rates per trap-night) and a surge in prevalence of antibody to EM virus in rodents, and the occurrence of the outbreak of disease in elephants

  1. Mineral dust effects on clouds and rainfall in the West African Sahel

    NASA Astrophysics Data System (ADS)

    Klüser, L.; Holzer-Popp, T.

    2010-03-01

    Aerosol cloud interactions are known to be of great importance to many parts of the climate system. Five years of observations from three different satellites (NASA EOS Aqua, Meteosat Second Generation and the Tropical Rainfall Measuring Mission) are used to statistically analyse the influence of mineral dust aerosol, separated from other aerosol species, on monsoon season cloudiness and precipitation in the West African Sahel domain. The aerosol-cloud-interactions were analysed separately by season and flow (air mass) in order to exclude spurious correlations with meteorological conditions. As expected from theory and previous case studies a reduction of precipitation due to reduced droplet sizes and suppression of convective activity under the influence of dust aerosol is evident from the analysis of this multiple year dataset. These results thus support the theory of a positive desertification feedback loop of mineral dust aerosol from a large-scale dataset.

  2. Red-ox speciation and mixing state of iron in individual African dust particles

    NASA Astrophysics Data System (ADS)

    Deboudt, Karine; Gloter, Alexandre; Mussi, Alexandre; Flament, Pascal

    2012-06-01

    The Fe distribution in African dust particles collected in Senegal (North-Western Africa) during the African Monsoon Multidisciplinary Analysis Special Observation Period 0 (AMMA-"SOP 0," February 2006) was assessed using individual particle analysis (Scanning and Transmission Electron Microscopy respectively equipped with X-ray Spectrometry (SEM-EDX) and Electron Energy Loss Spectrometry (TEM-EELS)). Senegal is not a dust source area; the chemical composition of collected dusts indicates that they originate primarily in the North-Western Sahara, which is consistent with previous studies of the area. Fe can be present inside dust particles as a substitution element in the crystalline lattice of aluminosilicate, but a high proportion (62%) of aluminosilicate Fe-containing particles are also found as an internal mixture of aluminosilicate with Fe oxide grains (including both oxide and hydroxide species). The 3D structure of such particles obtained by tomography reveals that these Fe-rich inclusions are often found at the surface of aluminosilicate particles but that some are also included inside particles. These Fe oxide grains can result from crustal earth or atmospheric processes during long-range transport. FeIII is dominant in both the aluminosilicate matrix and the Fe oxide grains (FeIII/Σ Fe ratio = 76.8% and 90.0%, respectively, on average), with notable heterogeneities of Fe valence inside grains at a nanometer scale.

  3. Long-range transport of mineral dust in the global atmosphere: Impact of African dust on the environment of the southeastern United States

    PubMed Central

    Prospero, Joseph M.

    1999-01-01

    Soil dust is a major constituent of airborne particles in the global atmosphere. Dust plumes frequently cover huge areas of the earth; they are one of the most prominent and commonly visible features in satellite imagery. Dust is believed to play a role in many biogeochemical processes, but the importance of dust in these processes is not well understood because of the dearth of information about the global distribution of dust and its physical, chemical, and mineralogical properties. This paper describes some features of the large-scale distribution of dust and identifies some of the geological characteristics of important source areas. The transport of dust from North Africa is presented as an example of possible long-range dust effects, and the impact of African dust on environmental processes in the western North Atlantic and the southeastern United States is assessed. Dust transported over long distances usually has a mass median diameter <10 μm. Small wind-borne soil particles show signs of extensive weathering; consequently, the physical and chemical properties of the particles will greatly depend on the weathering history in the source region and on the subsequent modifications that occur during transit in the atmosphere (typically a period of a week or more). To fully understand the role of dust in the environment and in human health, mineralogists will have to work closely with scientists in other disciplines to characterize the properties of mineral particles as an ensemble and as individual particles especially with regard to surface characteristics. PMID:10097049

  4. Size distribution and optical properties of long-range transported African dust

    NASA Astrophysics Data System (ADS)

    Formenti, Paola; Denjean, Cyrielle; Deboeufs, Karine; Laurent, Benoit; Chevaillier, Servanne; Maillé, Michel; Cazaunau, Mathieu; Vallejo, Pamela; Quinones, Mariana; Gutierrez-Molina, Ian; Cassola, Federico; Prati, Paolo; Andrews, Elisabeth; Ogren, John; Mayol-Bracero, Olga

    2015-04-01

    In the framework of the Dust Aging and Transport from Africa to the Caribbean (Dust-ATTAcK) project, a ground-based field campaign has been conducted at the Cape San Juan aerosol station in Puerto Rico, USA, (18.38°N 65.62°W) during June-July 2012. The aim of the field study was to document the physical and optical properties of long-range transported African dust, in order to reduce uncertainties on its effects on radiation and clouds. Several episodes of long-range transport of mineral dust lasting one-to-three days were observed almost every second day. Dust mostly generated from sources in Mauritania, Western Sahara and Algeria, and remained airborne for approximately seven days before being sampled. The number size distribution of mineral dust, measured between 10 nm and 20 µm by a combination of Scanning Mobility Particle Sizer and an optical particle counter, showed that dust was generally characterized by three modes in the ultrafine, accumulation and coarse mode. Whereas their amplitude changed, their modal diameter remained constant with time.. The particle fraction below 100 nm showed the highest variability as a consequence of mixing which anthropogenic pollution which occurred any time the trade winds blown from the south east before reaching the sampling site. Mass scattering and absorption efficiency, and single scattering albedo have been calculated based on measurements of scattering and absorption coefficients and mass concentrations. For particles in the PM10 fraction, the mass scattering efficiency at 450 nm was of the order of 1.4 m2 g-1 and the mass absorption efficiency at 467 nm of the order of 0.05 m2 g-1. The single scattering albedo at 450 nm was of the order of 0.96.

  5. 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.

  6. Optical, physical and chemical properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Di Biagio, Claudia; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Loisil, Rodrigue; Triquet, Sylvain; Zapf, Pascal; Roberts, Greg; Bourrianne, Thierry; Torres, Benjamin; Blarel, Luc; Sellegri, Karine; Freney, Evelyn; Schwarzenbock, Alfons; Ravetta, François; Laurent, Benoit; Mallet, Marc; Formenti, Paola

    2014-05-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), two intensive airborne campaigns (TRAQA, TRansport and Air QuAlity, 18 June - 11 July 2012, and ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) have been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to

  7. Properties of transported African mineral dust aerosols in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Chevaillier, Servanne; Gaimoz, Cécile; Grand, Noel; Triquet, Sylvain; Zapf, Pascal; Loisil, Rodrigue; Bourrianne, Thierry; Freney, Evelyn; Dupuy, Regis; Sellegri, Karine; Schwarzenbock, Alfons; Torres, Benjamin; Mallet, Marc; Cassola, Federico; Prati, Paolo; Formenti, Paola

    2015-04-01

    The transport of mineral dust aerosols is a global phenomenon with strong climate implications. Depending on the travel distance over source regions, the atmospheric conditions and the residence time in the atmosphere, various transformation processes (size-selective sedimentation, mixing, condensation of gaseous species, and weathering) can modify the physical and chemical properties of mineral dust, which, in turn, can change the dust's optical properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of these properties, and their temporal evolution with transport time. Within the frame of the ChArMex project (Chemistry-Aerosol Mediterranean experiment, http://charmex.lsce.ipsl.fr/), one intensive airborne campaign (ADRIMED, Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region, 06 June - 08 July 2013) has been performed over the Central and Western Mediterranean, one of the two major transport pathways of African mineral dust. In this study we have set up a systematic strategy to determine the optical, physical and optical properties of mineral dust to be compared to an equivalent dataset for dust close to source regions in Africa. This study is based on airborne observations onboard the SAFIRE ATR-42 aircraft, equipped with state of the art in situ instrumentation to measure the particle scattering and backscattering coefficients (nephelometer at 450, 550, and 700 nm), the absorption coefficient (PSAP at 467, 530, and 660 nm), the extinction coefficient (CAPS at 530 nm), the aerosol optical depth (PLASMA at 340 to 1640 nm), the size distribution in the extended range 40 nm - 30 µm by the combination of different particle counters (SMPS, USHAS, FSSP, GRIMM) and the chemical composition obtained by filter sampling. The chemistry and transport model CHIMERE-Dust have been used to classify the air masses according to the dust origin and transport. Case studies of dust transport

  8. The Dust at Altitude Recovery Technology (DART) System was Developed to Recover Plant, Human, and Animal Pathogens in Asian and African Dust Storms over North America

    NASA Astrophysics Data System (ADS)

    Schuerger, A. C.; Tench, B.; Nehr, A.; Emmons, T.; Valbuena, F.; Palaia, J.; Sugars, C.

    2014-12-01

    Dust emanates year-round from Africa and Asia and impacts air quality in North America. Asian dust plumes deliver up to 64 million tonnes of dust over the NW of the USA, and African dust storms deliver over 50 million tonnes of dust over Florida each year. Several recent studies have demonstrated that human and plant pathogens from Asian [1] African [2] aerosols can be transported to N. America in naturally occurring dust storms. What is unknown is whether these 'presumptive pathogens' impact human, plant, or animal health in the USA. In order to initiate a long-term monitoring program of pathogens in Asian and African dust plumes, we have developed a dust collection system called DART (Dust at Altitude Recovery Technology) (figure). The DART dust sampler can be mounted on a F104 Starfighter jet (figure) and a T6 Texan propeller driven airplane (not shown), and was test flown over FL in Dec. 2013 on the F104 and on the T6 in the summer of 2014. The DART system utilizes a high-volume pump to pass air through 6 separate filtration units where both aerosols and microbial cells are captured. The filtration systems exhibit flow rates from 25-142 L/min depending on the pore size and brand of filters used. Flow rates are directly correlated to increased air speed, and are inversely correlated to increased altitude. Filtration units can be turned on and off individually as required for specific science flight objectives. The DART dust sampler has performed nominally up to 7600 m, 0.92 Mach, and 3.5 +G's. During initial test flights in Dec. 2013, 5 of 8 genera of fungi recovered from the lower atmosphere over FL contained plant pathogens including species in the genera: Acremonium, Aspergillus, Cladosporium, Curvularia, and Fusarium. Numbers of recovered fungi, but not bacteria, increased significantly when 5 or 10 µm filters were used in the DART system compared to filter pore sizes ≤ 1.2 µm. Future sampling programs for both Asian and African dust events will be

  9. African horse sickness: The potential for an outbreak in disease-free regions and current disease control and elimination techniques.

    PubMed

    Robin, M; Page, P; Archer, D; Baylis, M

    2016-09-01

    African horse sickness (AHS) is an arboviral disease of equids transmitted by Culicoides biting midges. The virus is endemic in parts of sub-Saharan Africa and official AHS disease-free status can be obtained from the World Organization for Animal Health on fulfilment of a number of criteria. AHS is associated with case fatality rates of up to 95%, making an outbreak among naïve horses both a welfare and economic disaster. The worldwide distributions of similar vector-borne diseases (particularly bluetongue disease of ruminants) are changing rapidly, probably due to a combination of globalisation and climate change. There is extensive evidence that the requisite conditions for an AHS epizootic currently exist in disease-free countries. In particular, although the stringent regulations enforced upon competition horses make them extremely unlikely to redistribute the virus, there are great concerns over the effects of illegal equid movement. An outbreak of AHS in a disease free region would have catastrophic effects on equine welfare and industry, particularly for international events such as the Olympic Games. While many regions have contingency plans in place to manage an outbreak of AHS, further research is urgently required if the equine industry is to avoid or effectively contain an AHS epizootic in disease-free regions. This review describes the key aspects of AHS as a global issue and discusses the evidence supporting concerns that an epizootic may occur in AHS free countries, the planned government responses, and the roles and responsibilities of equine veterinarians. PMID:27292229

  10. Catchment response to bark beetle outbreak and dust-on-snow in the Colorado Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Livneh, Ben; Deems, Jeffrey S.; Buma, Brian; Barsugli, Joseph J.; Schneider, Dominik; Molotch, Noah P.; Wolter, K.; Wessman, Carol A.

    2015-04-01

    Since 2002, the headwaters of the Colorado River and nearby basins have experienced extensive changes in land cover at sub-annual timescales. Widespread tree mortality from bark beetle infestation has taken place across a range of forest types, elevation, and latitude. Extent and severity of forest structure alteration have been observed through a combination of aerial survey, satellite remote-sensing, and in situ measurements. Additional perturbations have resulted from deposition of dust from regional dry-land sources on mountain snowpacks that strongly alter the snow surface albedo, driving earlier and faster snowmelt runoff. One challenge facing past studies of these forms of disturbance is the relatively small magnitude of the disturbance signals within the larger climatic signal. The combined impacts of forest disturbance and dust-on-snow are explored within a hydrologic modeling framework. We drive the Distributed Hydrology Soil and Vegetation Model (DHSVM) with observed meteorological data, time-varying maps of leaf area index and forest properties to emulate bark beetle impacts, and parameterizations of snow albedo based on observations of dust forcing. Results from beetle-killed canopy alteration suggest slightly greater snow accumulation as a result of less interception and reduced canopy sublimation and evapotranspiration, contributing to overall increases in annual water yield between 8% and 13%. However, understory regeneration roughly halves the changes in water yield. A purely observation-based estimate of runoff coefficient change with cumulative forest mortality shows comparable sensitivities to simulated results; however, positive water yield changes are not statistically significant (p ⩽ 0.05). The primary hydrologic impact of dust-on-snow forcing is an increased rate of snowmelt associated with more extreme dust deposition, producing earlier peak streamflow rates on the order of 1-3 weeks. Simulations of combined bark beetle and dust

  11. African Dust Fertilizing the Amazon Rainforest: An Assessment with Seven-year Record of CALIOP Measurements

    NASA Astrophysics Data System (ADS)

    Yu, H.; Chin, M.; Yuan, T.; Bian, H.; Prospero, J. M.; Omar, A. H.; Remer, L. A.; Winker, D. M.; Yang, Y.; Zhang, Y.; Zhang, Z.

    2014-12-01

    The productivity of Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of transported African dust in boreal winter and spring is considered an important nutrient input for the Amazon Basin, though its magnitude is not well qunatified. This study provides a remote sensing observation-based estimate of dust deposition in the Amazon Basin using a 7-year (2007-2013) record of three dimensional (3D) distributions of aerosol in both cloud-free and above-cloud conditions from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). It is estimated that the 7-year average of dust deposition into the Amazon Basin amounts to 15.1 ~ 32.1 Tg a-1 (Tg = 1012 g). This imported dust could provide 0.012 ~ 0.025 Tg P a-1 or equivalent to 12 ~ 26 g P ha-1 a-1 to fertilize the Amazon rainforest, which largely compensates the hydrological loss of P. The CLAIOP-based estimate agrees better with estimates from in-situ measurements and model simulations than what has been reported in literature. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The trans-Atlantic transport and deposition of dust shows strong interannual variations that are found to correlate with the North Atlantic Oscillation index in the winter season and anticorrelate with the prior-year Sahel Precipitation Index on an annual basis. Uncertainties associated with the estimate will also be discussed.

  12. Aerosol Optical Thickness in the Presence and Absence of African Dust using AERONET and Microtops II Sunphotometers

    NASA Astrophysics Data System (ADS)

    Ruiz, A.; Raizada, S.; Tepley, C. A.; Venero, I.; Zurcher, F.; Mayol-Bracero, O. L.

    2011-12-01

    As part of the Puerto Rico African Dust and Cloud Study (PRADACS) Project, we present a comparison of the aerosol optical thickness (AOT) between the AERONET sunphotometer (CIMEL Electronique 318A) located at Cape San Juan (CSJ, 18° 23' N, 65° 37' E), Puerto Rico, and the radiometers (Microtops II) of the Arecibo Observatory. Data were collected at CSJ during the summer period of 2011, when African dust was present most of the time. Preliminary results showed, for both instruments, AOT values around of 0.4 when there were high concentrations of African dust over the island Puerto Rico. The AOT correlations between the two instruments were very good, with a slope of 0.8 and r2 of 0.9 for all wavelengths. The main differences observed were on the values above 0.6. We will show the temporal behavior of AOT for the two instruments and the spatial differences between them.

  13. Genetic Evidence for Rift Valley Fever Outbreaks in Madagascar Resulting from Virus Introductions from the East African Mainland rather than Enzootic Maintenance▿†‡

    PubMed Central

    Carroll, Serena A.; Reynes, Jean-Marc; Khristova, Marina L.; Andriamandimby, Soa Fy; Rollin, Pierre E.; Nichol, Stuart T.

    2011-01-01

    Rift Valley fever virus (RVFV), a mosquito-borne phlebovirus, has been detected in Madagascar since 1979, with occasional outbreaks. In 2008 to 2009, a large RVFV outbreak was detected in Malagasy livestock and humans during two successive rainy seasons. To determine whether cases were due to enzootic maintenance of the virus within Madagascar or to importation from the East African mainland, nine RVFV whole genomic sequences were generated for viruses from the 1991 and 2008 Malagasy outbreaks. Bayesian coalescent analyses of available whole S, M, and L segment sequences were used to estimate the time to the most recent common ancestor for the RVFVs. The 1979 Madagascar isolate shared a common ancestor with strains on the mainland around 1972. The 1991 Madagascar isolates were in a clade distinct from that of the 1979 isolate and shared a common ancestor around 1987. Finally, the 2008 Madagascar viruses were embedded within a large clade of RVFVs from the 2006–2007 outbreak in East Africa and shared a common ancestor around 2003 to 2004. These results suggest that the most recent Madagascar outbreak was caused by a virus likely arriving in the country some time between 2003 and 2008 and that this outbreak may be an extension of the 2006–2007 East African outbreak. Clustering of the Malagasy sequences into subclades indicates that the viruses have continued to evolve during their short-term circulation within the country. These data are consistent with the notion that RVFV outbreaks in Madagascar result not from emergence from enzootic cycles within the country but from recurrent virus introductions from the East African mainland. PMID:21507967

  14. Assessment of African and local wind-blown dust contributions at three rural sites in SE Spain: aerosol size distribution

    NASA Astrophysics Data System (ADS)

    Orza, J. A. G.; Cabello, M.; Lidón, V.; Martínez, J.

    2009-04-01

    Aerosol number size distribution and meteorological parameters were measured at three rural sites in semiarid southeastern Spain. Number concentrations of suspended particles in 31 size bins between 0.25 and 32 m diameter were continuosly recorded with a GRIMM 190 aerosol spectrometer at: (i) a rural background (RB) location in a perennial tussock grassland, from July to October 2006; (ii) a rural site surrounded by abandoned croplands, and influenced by mineral industries and by a small paved road having a small traffic load located 30 m to the East (RA), from June to December 2007; and (iii) a rural (R) location in an agricultural plot previously cleared and then lightly leveled and compacted for future lemon-tree cultivation, from February to June 2008. Events of long range transport from North Africa to the study area (African dust outbreaks, ADOs) were identified by aerosol transport models, back-trajectories and satellite imagery. There is an increase in the concentration of particles larger than 2 m with increasing wind speed while the concentrations decrease for smaller particles at the RB and R sites. At the RA location, that increase is observed for particles in the range 1.6 - 3.5 m (the precise value depends on the wind speed) when there are West winds. Particulate resuspension is found to occur at all wind speeds, although wind threshold values can be identified by a sharp increase in particle concentrations for a range of particle sizes. Light winds entrain large particles while stronger winds additionally entrain particles of smaller size (down to 2.5 m for the highest winds). The size distributions present maxima at 1.6 and 3 m on days with ADO. Concentration for almost every particle size is higher on ADOs than on days without such events, due in part to the associated meteorological situation. This work was partially supported by the Spanish Ministerio de Educación y Ciencia under grant CGL2004-04419 (RESUSPENSE Project).

  15. Relationship between African dust carried in the Atlantic trade winds and surges in pediatric asthma attendances in the Caribbean

    NASA Astrophysics Data System (ADS)

    Prospero, Joseph M.; Blades, Edmund; Naidu, Raana; Mathison, George; Thani, Haresh; Lavoie, Marc C.

    2008-11-01

    Asthma is epidemic in developed and developing countries including those in the Caribbean where it is widely believed that African dust, transported in high concentrations in the Trade Winds every year, is a major causative factor. The link between asthma and dust in the Caribbean is based largely on anecdotal evidence that associates sharp increases in the occurrence of asthma symptoms with hazy conditions often caused by dust. Here we report on a 2-year study of the relationship between the daily concentrations of dust measured in on-shore Trade Winds at Barbados and pediatric asthma attendance rates at Queen Elizabeth Hospital (QEH). We looked for large increases in QEH daily attendances in relation to daily dust concentrations as previously suggested by anecdotal observations. We could not find any obvious relationship although there may be more subtle linkages between dust and asthma. Our measurements show, however, that the concentration of dust in the size range under 2.5 μm diameter is sufficiently high as to challenge United States Environmental Protection Agency air quality standards for respirable particles. Thus, African dust may constitute a health threat of a different nature, producing symptoms less obvious than those of asthma.

  16. 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.

  17. 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.

  18. The Impact of Projected Changes in Monsoon Season Circulation and African Easterly Waves on Saharan Dust Transport

    NASA Astrophysics Data System (ADS)

    Skinner, C. B.; Diffenbaugh, N. S.

    2013-12-01

    The Sahara is the largest source region of mineral dust in the world. Each year, an estimated 100 to 700 million tons of dust are transported from the Sahara through atmospheric processes. Roughly 30 - 50% of this dust travels westward into the North Atlantic where it impacts the regional radiative balance, atmospheric dynamics, and biogeochemical cycles. During the boreal summer season, dust emissions and dust transport over North Africa are largely controlled by westward propagating synoptic-scale and mesoscale systems such as African easterly waves (AEWs) and mesoscale convective systems (MCSs). In particular, strong low-level winds, vertical motion, and convection associated with these systems drive dust mobilization and vertical mixing throughout the atmosphere. In this work we utilize the CMIP5 ensemble of general circulation models to explore the projected impact of enhanced radiative forcing, consistent with a high emissions scenario (RCP8.5), on atmospheric processes that may influence the emission and transport of dust over West Africa. In particular we focus on the simulation of AEWs during the months of the West African monsoon (June - September). Results from the CMIP5 ensemble indicate a robust increase in low-level (850mb) AEW activity along the Sahel/Sahara border in response to increasing greenhouse gas concentrations by the end of the 21st century. Across the CMIP5 ensemble, AEWs exhibit the strongest increase in low-level winds directly over the observed prolific dust sources within Mali, Mauritania and Algeria in the western Sahara. Enhanced AEW activity in this region is consistent with projected increases in low-level baroclinicity and increased ascent associated with a deepening Saharan Heat Low and stronger convergence along the Intertropical Front. We use a variety of observed and modeled relationships between atmospheric processes and dust as well as output from the available CMIP5 dust modules to explore the impact of the projected

  19. Need of surveillance response systems to combat Ebola outbreaks and other emerging infectious diseases in African countries

    PubMed Central

    2014-01-01

    There is growing concern in Sub-Saharan Africa about the spread of the Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, and the public health burden that it ensues. Since 1976, there have been 885,343 suspected and laboratory confirmed cases of EVD and the disease has claimed 2,512 cases and 932 fatality in West Africa. There are certain requirements that must be met when responding to EVD outbreaks and this process could incur certain challenges. For the purposes of this paper, five have been identified: (i) the deficiency in the development and implementation of surveillance response systems against Ebola and others infectious disease outbreaks in Africa; (ii) the lack of education and knowledge resulting in an EVD outbreak triggering panic, anxiety, psychosocial trauma, isolation and dignity impounding, stigmatisation, community ostracism and resistance to associated socio-ecological and public health consequences; (iii) limited financial resources, human technical capacity and weak community and national health system operational plans for prevention and control responses, practices and management; (iv) inadequate leadership and coordination; and (v) the lack of development of new strategies, tools and approaches, such as improved diagnostics and novel therapies including vaccines which can assist in preventing, controlling and containing Ebola outbreaks as well as the spread of the disease. Hence, there is an urgent need to develop and implement an active early warning alert and surveillance response system for outbreak response and control of emerging infectious diseases. Understanding the unending risks of transmission dynamics and resurgence is essential in implementing rapid effective response interventions tailored to specific local settings and contexts. Therefore, the following actions are recommended: (i) national and regional inter-sectorial and trans-disciplinary surveillance response systems that include early warnings, as well

  20. Trace-metal concentrations in African dust: effects of long-distance transport and implications for human health

    USGS Publications Warehouse

    Garrison, Virginia; Lamothe, Paul; Morman, Suzette; Plumlee, Geoffrey S.

    2010-01-01

    The Sahara and Sahel lose billions of tons of eroded mineral soils annually to the Americas and Caribbean, Europe and Asia via atmospheric transport. African dust was collected from a dust source region (Mali, West Africa) and from downwind sites in the Caribbean [Trinidad-Tobago (TT) and U.S. Virgin Islands (VI)] and analysed for 32 trace-elements. Elemental composition of African dust samples was similar to that of average upper continental crust (UCC), with some enrichment or depletion of specific trace-elements. Pb enrichment was observed only in dust and dry deposition samples from the source region and was most likely from local use of leaded gasoline. Dust particles transported long-distances (VI and TT) exhibited increased enrichment of Mo and minor depletion of other elements relative to source region samples. This suggests that processes occurring during long-distance transport of dust produce enrichment/depletion of specific elements. Bioaccessibility of trace-metals in samples was tested in simulated human fluids (gastric and lung) and was found to be greater in downwind than source region samples, for some metals (e.g., As). The large surface to volume ratio of the dust particles (<2.5 µm) at downwind sites may be a factor.

  1. Residency Training at the Front of the West African Ebola Outbreak: Adapting for a Rare Opportunity

    PubMed Central

    Mo, Yin; Archuleta, Sophia; Salmon, Sharon; Fisher, Dale

    2016-01-01

    Medical trainees face multiple barriers to participation in major outbreak responses such as that required for Ebola Virus Disease through 2014-2015 in West Africa. Hurdles include fear of contracting and importing the disease, residency requirements, scheduling conflicts, family obligations and lack of experience and maturity. We describe the successful four-week deployment to Liberia of a first year infectious diseases trainee through the mechanism of the Global Outbreak Alert and Response Network of the World Health Organization. The posting received prospective approval from the residency supervisory committees and employing hospital management and was designed with components fulfilling the Accreditation Council for Graduate Medical Education (ACGME) core competencies. It mirrored conventional training with regards to learning objectives, supervisory framework and assessment methods. Together with Centers for Disease Control and Prevention and many other partners, the team joined the infection prevention and control efforts in Monrovia. Contributions were made to a 'ring fencing' infection control approach that was being introduced, including enhancement of triage, training and providing supplies in high priority health-care facilities in the capital and border zones. In addition the fellow produced an electronic database that enabled monitoring infection control standards in health facilities. This successful elective posting illustrates that quality training can be achieved, even in the most challenging environments, with support from the pedagogic and sponsoring institutions. Such experiential learning opportunities benefit both the outbreak response and the trainee, and if scaled up would contribute towards building a global health emergency workforce. More should be done from residency accreditation bodies in facilitating postings in outbreak settings. PMID:27330848

  2. Residency Training at the Front of the West African Ebola Outbreak: Adapting for a Rare Opportunity.

    PubMed

    Mo, Yin; Archuleta, Sophia; Salmon, Sharon; Fisher, Dale

    2016-01-01

    Medical trainees face multiple barriers to participation in major outbreak responses such as that required for Ebola Virus Disease through 2014-2015 in West Africa. Hurdles include fear of contracting and importing the disease, residency requirements, scheduling conflicts, family obligations and lack of experience and maturity. We describe the successful four-week deployment to Liberia of a first year infectious diseases trainee through the mechanism of the Global Outbreak Alert and Response Network of the World Health Organization. The posting received prospective approval from the residency supervisory committees and employing hospital management and was designed with components fulfilling the Accreditation Council for Graduate Medical Education (ACGME) core competencies. It mirrored conventional training with regards to learning objectives, supervisory framework and assessment methods. Together with Centers for Disease Control and Prevention and many other partners, the team joined the infection prevention and control efforts in Monrovia. Contributions were made to a 'ring fencing' infection control approach that was being introduced, including enhancement of triage, training and providing supplies in high priority health-care facilities in the capital and border zones. In addition the fellow produced an electronic database that enabled monitoring infection control standards in health facilities. This successful elective posting illustrates that quality training can be achieved, even in the most challenging environments, with support from the pedagogic and sponsoring institutions. Such experiential learning opportunities benefit both the outbreak response and the trainee, and if scaled up would contribute towards building a global health emergency workforce. More should be done from residency accreditation bodies in facilitating postings in outbreak settings. PMID:27330848

  3. Geochemical evidence for African dust inputs to soils of western Atlantic islands: Barbados, the Bahamas, and Florida

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.; Prospero, J.M.; Carey, S.N.

    2007-01-01

    We studied soils on high-purity limestones of Quaternary age on the western Atlantic Ocean islands of Barbados, the Florida Keys, and the Bahamas. Potential soil parent materials in this region, external to the carbonate substrate, include volcanic ash from the island of St. Vincent (near Barbados), volcanic ash from the islands of Dominica and St. Lucia (somewhat farther from Barbados), the fine-grained component of distal loess from the lower Mississippi River Valley, and wind-transported dust from Africa. These four parent materials can be differentiated using trace elements (Sc, Cr, Th, and Zr) and rare earth elements that have minimal mobility in the soil-forming environment. Barbados soils have compositions that indicate a complex derivation. Volcanic ash from the island of St. Vincent appears to have been the most important influence, but African dust is a significant contributor, and even Mississippi River valley loess may be a very minor contributor to Barbados soils. Soils on the Florida Keys and islands in the Bahamas appear to have developed mostly from African dust, but Mississippi River valley loess may be a significant contributor. Our results indicate that inputs of African dust are more important to the genesis of soils on islands in the western Atlantic Ocean than previously supposed. We hypothesize that African dust may also be a major contributor to soils on other islands of the Caribbean and to soils in northern South America, central America, Mexico, and the southeastern United States. Dust inputs to subtropical and tropical soils in this region increase both nutrient-holding capacity and nutrient status and thus may be critical in sustaining vegetation. Copyright 2007 by the American Geophysical Union.

  4. On the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds

    PubMed Central

    Wang, Weijie; Evan, Amato T.; Flamant, Cyrille; Lavaysse, Christophe

    2015-01-01

    A large body of work has shown that year-to-year variations in North African dust emission are inversely proportional to previous-year monsoon rainfall in the Sahel, implying that African dust emission is highly sensitive to vegetation changes in this narrow transitional zone. However, such a theory is not supported by field observations or modeling studies, as both suggest that interannual variability in dust is due to changes in wind speeds over the major emitting regions, which lie to the north of the Sahelian vegetated zone. We reconcile this contradiction showing that interannual variability in Sahelian rainfall and surface wind speeds over the Sahara are the result of changes in lower tropospheric air temperatures over the Saharan heat low (SHL). As the SHL warms, an anomalous tropospheric circulation develops that reduces wind speeds over the Sahara and displaces the monsoonal rainfall northward, thus simultaneously increasing Sahelian rainfall and reducing dust emission from the major dust “hotspots” in the Sahara. Our results shed light on why climate models are, to date, unable to reproduce observed historical variability in dust emission and transport from this region. PMID:26601301

  5. 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.

  6. 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.

  7. Microbiological fingerprint of African dust deposition in alpine snow pack, Mont Blanc summit

    NASA Astrophysics Data System (ADS)

    Chuvochina, Maria; Alekhina, Irina; Normand, Philippe; Petit, Jean-Robert; Bulat, Sergey

    2010-05-01

    The biogeochemical effect of African dust transport has been reported mostly with respect to nutrient budget change in both terrestrial and aquatic ecosystems and global transport of microorganisms, including pathogens. However, its potential to seed or colonize the remote environments by transported microorganisms is poorly understood. This study has focused on bacterial content and diversity of Saharan dust deposition from 2006, 2008 and 2009 in snow pack of Mont Blanc (MtBl) glacier as well as recognition of bacteria which could be involved in establishing microbiota in this icy environment. Four snow samples recorded Saharan dust events from June 2006 (SDm06/2006 - 3,5 months aged), May and June 2008 (SDm05/2008 and SDm06/2008 - 1 month in between and 1 week aged each) and May 2009 (SDm05/2009 - 1 week aged) were collected at Col du Dome area (4250m a.s.l.). Bacterial community structure was assessed by ribotyping and subsequent sequencing of bacterial 16S rRNA genes. To exclude human-associated and laboratory contamination several controls were run in parallel updating our contaminant library. The obtained phylotypes were tested against this library keeping only those which successfully passed through this exam. Of 176 selected clones from four clone libraries 29.8% were met in our contaminant library. The ‘true' sequences were assigned to 57 phylotypes (>97.5% sequence similarity) originating mostly from soil. The prevalent phylotypes recovered were belonging to different bacterial divisions: Deinococcus-Thermus, Alpha-proteobacteria and CFB groups for SDm06/2006; Actinobacteria, Alpha-proteobacteria and CFB for SDm05/2008 and SDm06/2008; Actinobacteria and chloroplasts/plastids for SDm05/2009. Phylogenetic analysis of all phylotypes showed no shared species amongst all 4 dust layers in MtBl snow pack in 2006, 2008 and 2009. However, two phylotypes (Blastococcus saxobsidens sp. - 99%, Geodermatophilus obscurus sp. - 99%) were shared between 2008 and 2009

  8. Radiative Effects of African Dust and Smoke Observed from CERES and CALIOP Data

    NASA Technical Reports Server (NTRS)

    Yorks, John E.; McGill, Matt; Rodier, Sharon; Vaughan, Mark; Xu, Yongxiang; Hlavka, Dennis

    2009-01-01

    Cloud and aerosol effects have a significant impact on the atmospheric radiation budget in the Tropical Atlantic because of the spatial and temporal extent of desert dust and smoke from biomass burning in the atmosphere. The influences of African dust and smoke aerosols on cloud radiative properties over the Tropical Atlantic Ocean were analyzed for the month of July for three years (2006-2008) using collocated data collected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Clouds and the Earth s Radiant Energy System (CERES) instruments on the CALIPSO and Aqua satellites. Aerosol layer height and type can be more accurately determined using CALIOP data, through parameters such as cloud and aerosol layer height, optical depth and depolarization ratio, than data from atmospheric imagers used in previous cloud-aerosol interaction studies. On average, clouds below 5 km had a daytime instantaneous shortwave (SW) radiative flux of 270.2 +/- 16.9 W/sq m and thin cirrus clouds had a SW radiative flux of 208.0 +/- 12.7 W/sq m. When dust aerosols interacted with clouds below 5 km, as determined from CALIPSO, the SW radiative flux decreased to 205.4 +/- 13.0 W/sq m. Similarly, smoke aerosols decreased the SW radiative flux of low clouds to a value of 240.0 +/- 16.6 W/sq m. These decreases in SW radiative flux were likely attributed to the aerosol layer height and changes in cloud microphysics. CALIOP lidar observations, which more accurately identify aerosol layer height than passive instruments, appear essential for better understanding of cloud-aerosol interactions, a major uncertainty in predicting the climate system.

  9. Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

    NASA Astrophysics Data System (ADS)

    Nastos, P. T.; Bleta, A. G.; Matsangouras, I. T.

    2016-01-01

    Crete Island is located in the southmost border of East Mediterranean basin, facing exacerbating atmospheric conditions (mainly concentrations of particulates) due to Saharan dust outbreaks. It is worth to note that these episodes are more frequent during spring and autumn, when mild biometeorological conditions become intolerable due to the synergy of the so called Föhn winds. Cretan mountains, especially Psiloritis Mt. (summit at 2456 m), are orientated perpendicularly to the southwest air mass flow, generating the Föhn winds. Propagating from the leeward of the mountains, these dry, hot winds have an effect on prevailing biometeorological conditions. While descending to the lowlands on the leeward side of the range, the wind becomes strong, gusty, and desiccating. This wind often lasts less than an hour to several days, with gradual weakening after the first or the second day. Sometimes, it stops very abruptly. In this work, the authors examined and analyzed the abrupt changes of human thermal perception within specific case studies during which Föhn winds appeared in Heraklion city at the leeward of Psiloritis Mt, associated with extreme Saharan dust episodes, observed within the period 2006-2010. In order to verify the development of Föhn winds, Meteorological Terminal Aviation Routine Weather Reports (METARs, meteorological observations every half hour), were acquired from the Heraklion meteorological station installed by the Hellenic National Meteorological Service (HNMS). The biometeorological conditions analyzed are based on human thermal bioclimatic indices such as the Physiologically equivalent temperature (PET) and the Universal Thermal Climate Index (UTCI). METAR recordings of meteorological variables, such as air temperature, vapor pressure, wind speed, and cloudiness, were used as input variables in modeling the aforementioned thermal indices, so that to interpret the grade of the thermo-physiological stress. The PET and UTCI analysis was

  10. Transport of North African dust from the Bodélé depression to the Amazon Basin: a case study

    NASA Astrophysics Data System (ADS)

    Ben-Ami, Y.; Koren, I.; Rudich, Y.; Artaxo, P.; Martin, S. T.; Andreae, M. O.

    2010-08-01

    Through long-range transport of dust, the North-African desert supplies essential minerals to the Amazon rain forest. Since North African dust reaches South America mostly during the Northern Hemisphere winter, the dust sources active during winter are the main contributors to the forest. Given that the Bodélé depression area in southwestern Chad is the main winter dust source, a close link is expected between the Bodélé emission patterns and volumes and the mineral supply flux to the Amazon. Until now, the particular link between the Bodélé and the Amazon forest was based on sparse satellite measurements and modeling studies. In this study, we combine a detailed analysis of space-borne and ground data with reanalysis model data and surface measurements taken in the central Amazon during the Amazonian Aerosol Characterization Experiment (AMAZE-08) in order to explore the validity and the nature of the proposed link between the Bodélé depression and the Amazon forest. This case study follows the dust events of 11-16 and 18-27 February 2008, from the emission in the Bodélé over West Africa (most likely with contribution from other dust sources in the region) the crossing of the Atlantic Ocean, to the observed effects above the Amazon canopy about 10 days after the emission. The dust was lifted by surface winds stronger than 14 m s-1, usually starting early in the morning. The lofted dust, mixed with biomass burning aerosols over Nigeria, was transported over the Atlantic Ocean, and arrived over the South American continent. The top of the aerosol layer reached above 3 km, and the bottom merged with the boundary layer. The arrival of the dusty air parcel over the Amazon forest increased the average concentration of aerosol crustal elements by an order of magnitude.

  11. The Fertilizing Role of African Dust in the Amazon Rainforest: A First Multiyear Assessment Based on CALIPSO Lidar Observations

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Remer, Lorraine A.; Prospero, Joseph M.; Omar, Ali; Winker, David; Yang, Yuekui; Zhang, Yan; Zhang, Zhibo; Zhao, Chun

    2015-01-01

    The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three dimensional (3D) aerosol measurements over 2007-2013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7-year average of dust deposition into the Amazon Basin is estimated to be 28 (8 to approximately 48) Tg a(exp -1) or 29 (8 to approximately 50) kg ha(exp -1) a(exp -1). The dust deposition shows significant interannual variation that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multi-year mean estimate of dust deposition matches better with estimates from in-situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.0060.037) Tg P of phosphorus per year, equivalent to 23 (7 to approximately 39) g P ha(exp -1) a(exp -1) to fertilize the Amazon rainforest. This out-of-Basin P input largely compensates the hydrological loss of P from the Basin, suggesting an important role of African dust in preventing phosphorus depletion on time scales of decades to centuries.

  12. Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period

    NASA Astrophysics Data System (ADS)

    Pausata, Francesco S. R.; Messori, Gabriele; Zhang, Qiong

    2016-01-01

    The West African Monsoon (WAM) is crucial for the socio-economic stability of millions of people living in the Sahel. Severe droughts have ravaged the region in the last three decades of the 20th century, highlighting the need for a better understanding of the WAM dynamics. One of the most dramatic changes in the West African Monsoon (WAM) occurred between 15000-5000 yr BP, when increased summer rainfall led to the so-called "Green Sahara" and to a reduction in dust emissions from the region. However, model experiments are unable to fully reproduce the intensification and geographical expansion of the WAM during this period, even when vegetation over the Sahara is considered. Here, we use a fully coupled simulation for 6000 yr BP (Mid-Holocene) in which prescribed Saharan vegetation and dust concentrations are changed in turn. A closer agreement with proxy records is obtained only when both the Saharan vegetation changes and dust decrease are taken into account. The dust reduction strengthens the vegetation-albedo feedback, extending the monsoon's northern limit approximately 500 km further than the vegetation-change case only. We therefore conclude that accounting for changes in Saharan dust loadings is essential for improving model simulations of the WAM during the Mid-Holocene.

  13. Rain chemistry and cloud composition and microphysics in a Caribbean tropical montane cloud forest under the influence of African dust

    NASA Astrophysics Data System (ADS)

    Torres-Delgado, Elvis; Valle-Diaz, Carlos J.; Baumgardner, Darrel; McDowell, William H.; González, Grizelle; Mayol-Bracero, Olga L.

    2015-04-01

    It is known that huge amounts of mineral dust travels thousands of kilometers from the Sahara and Sahel regions in Africa over the Atlantic Ocean reaching the Caribbean, northern South America and southern North America; however, not much is understood about how the aging process that takes place during transport changes dust properties, and how the presence of this dust affects cloud's composition and microphysics. This African dust reaches the Caribbean region mostly in the summer time. In order to improve our understanding of the role of long-range transported African dust (LRTAD) in cloud formation processes in a tropical montane cloud forest (TMCF) in the Caribbean region we had field campaigns measuring dust physical and chemical properties in summer 2013, as part of the Puerto Rico African Dust and Cloud Study (PRADACS), and in summer 2014, as a part of the Luquillo Critical Zone Observatory (LCZO) and in collaboration with the Saharan Aerosol Long-Range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE). Measurements were performed at the TMCF of Pico del Este (PE, 1051 masl) and at the nature reserve of Cabezas de San Juan (CSJ, 60 masl). In both stations we monitored meteorological parameters (e.g., temperature, wind speed, wind direction). At CSJ, we measured light absorption and scattering at three wavelengths (467, 528 and 652 nm). At PE we collected cloud and rainwater and monitored cloud microphysical properties (e.g., liquid water content, droplet size distribution, droplet number concentration, effective diameter and median volume diameter). Data from aerosol models, satellites, and back-trajectories were used together with CSJ measurements to classify air masses and samples collected at PE in the presence or absence of dust. Soluble ions, insoluble trace metals, pH and conductivity were measured for cloud and rainwater. Preliminary results for summer 2013 showed that in the presence of LRTAD (1) the average conductivity of cloud water

  14. The Role of African Dust Particles on Cloud Chemistry and Microphysics in a Tropical Montane Cloud Forest in the Caribbean

    NASA Astrophysics Data System (ADS)

    Torres-Delgado, E.; Valle-Diaz, C. J.; Baumgardner, D.; McDowell, W. H.; Gonzalez, G.; Mayol-Bracero, O. L.

    2015-12-01

    Huge amounts of African dust travels thousands of kilometers from the Sahara and Sahel regions to the Caribbean, northern South America and southern North America. However, not much is understood about how the aging process that takes place during transport changes dust properties, and how it affects cloud's composition and microphysics. In order to improve our understanding of the role of long-range transported African dust (LRTAD) in cloud formation processes we had field campaigns measuring dust physical and chemical properties in summers of 2013, 2014 and 2015, as part of the Puerto Rico African Dust and Cloud Study (PRADACS), and of the Luquillo Critical Zone Observatory (LCZO). Measurements were performed at the tropical montane cloud forest (TMCF) of Pico del Este (PE, 1051 masl) and at the nature reserve of Cabezas de San Juan (CSJ, 60 masl). In both ground stations we monitored meteorological parameters (e.g., temperature, wind speed, wind direction). At CSJ, we measured light absorption and scattering at three wavelengths (467, 528 and 652 nm). At PE we collected cloud and rainwater for chemical analyses and monitored cloud microphysical properties (e.g., liquid water content, droplet size distribution, droplet number concentration, effective diameter and median volume diameter). Summer 2015 was the first attempt to characterize microphysical properties of the summer period (June to August) at PE, where dust is in its higher concentrations of the year. Samples were classified using data from models and satellites together with CSJ measurements as low or high dust influenced. Soluble ions, insoluble trace metals, pH, conductivity, total and dissolved organic carbon and total and dissolved nitrogen were measured for cloud and rainwater. Enrichment factor analysis was used to determine sea and crustal contribution of species by sample, as well as the neutralization factor and fractional acidity. Some preliminary results show cloud water conductivity for low

  15. Fungal Spore Concentrations and Ergosterol Content in Aerosol Samples in the Caribbean During African Dust Events

    NASA Astrophysics Data System (ADS)

    Santos-Figueroa, G.; Bolaños-Rosero, B.; Mayol-Bracero, O. L.

    2015-12-01

    Fungal spores are a major component of primary biogenic aerosol particles that are emitted to the atmosphere, are ubiquitous, and play an important role in the chemistry and physics of the atmosphere, climate, and public health. Every year, during summer months, African dust (AD) particles are transported to the Caribbean region causing an increase in the concentrations of particulate matter in the atmosphere. AD is one of the most important natural sources of mineral particulate matter at the global scale, and many investigations suggest that it has the ability to transport dust-associated biological particles through long distances. The relationship between AD incursions and the concentration of fungal spores in the Caribbean region is poorly understood. In order to investigate the effects of AD incursions on fungal spore's emissions, fungal spore concentrations were monitored using a Burkard spore trap at the tropical montane cloud forest of Pico del Este at El Yunque National Forest, Puerto Rico. The presence of AD was supported with satellite images of aerosol optical thickness, and with the results from the air masses backward trajectories calculated with the NOAA HYSPLIT model. Basidiospores and Ascospores comprised the major components of the total spore's concentrations, up to a maximum of 98%, during both AD incursions and background days. A considerably decrease in the concentration of fungal spores during AD events was observed. Ergosterol, biomarker for measuring fungal biomass, concentrations were determined in aerosols that were sampled at a marine site, Cabezas de San Juan Nature Reserve, in Fajardo Puerto Rico, and at an urban site, Facundo Bueso building at the University of Puerto Rico. Additional efforts to understand the relationship between the arrival of AD to the Caribbean and a decrease in spore's concentrations are needed in order to investigate changes in local spore's vs the contribution of long-range spores transported within the AD.

  16. Assessing the performance of methods to detect and quantify African dust in airborne particulates.

    PubMed

    Viana, Mar; Salvador, Pedro; Artíñano, Begoña; Querol, Xavier; Alastuey, Andrés; Pey, Jorge; Latz, Achim J; Cabañas, Mercè; Moreno, Teresa; García dos Santos, Saúl; Herce, María Dolores; Diez Hernández, Pablo; Romero García, Dolores; Fernández-Patier, Rosalía

    2010-12-01

    African dust (AD) contributions to particulate matter (PM) levels may be reported by Member States to the European Commission during justification of exceedances of the daily limit value (DLV). However, the detection and subsequent quantification of the AD contribution to PM levels is complex, and only two measurement-based methods are available in the literature: the Spanish-Portuguese reference method (SPR), and the Tel Aviv University method (TAU). In the present study, both methods were assessed. The SPR method was more conservative in the detection of episodes (71 days identified as AD by SPR, vs 81 by TAU), as it is less affected by interferences with local dust sources. The mean annual contribution of AD was lower with the TAU method than with SPR (2.7 vs 3.5 ± 1.5 μg/m(3)). The SPR and TAU AD time series were correlated with daily aluminum levels (a known tracer of AD), as well as with an AD source identified by the Positive Matrix Factorization (PMF) receptor model. Higher r(2) values were obtained with the SPR method than with TAU in both cases (r(2) = 0.72 vs 0.56, y = 0.05x vs y = 0.06x with aluminum levels; r(2)=0.79 vs 0.43, y = 0.8x vs y = 0.4x with the PMF source). We conclude that the SPR method is more adequate from an EU policy perspective (justification of DLV exceedances) due to the fact that it is more conservative than the TAU method. Based on our results, the TAU method requires adaptation of the thresholds in the algorithm to refine detection of low-impact episodes and avoid misclassification of local events as AD. PMID:21049991

  17. Aerosol chemical and radiative properties in the tropical Atlantic trade winds: The importance of African mineral dust

    NASA Astrophysics Data System (ADS)

    Li-Jones, Xu

    This dissertation presents results relevant to aerosol radiative forcing. The focus of this dissertation is the role of mineral dust in atmospheric radiative processes over the tropical Atlantic Ocean. The aerosol mass and light scattering data concurrently measured over the tropical North Atlantic ocean yield a dust mass scattering efficiency of 0.77 m2/g, about a quarter of that measured for non-sea-salt sulfate (nss SO4=) in the North Atlantic marine boundary layer. Because of the high concentration of mineral dust relative to nss SO4= over the tropical North Atlantic, the total scattering by mineral dust is about four times that by nss SO4 = aerosol in this region. On an annual basis, aerosol optical depth is apportioned to: mineral dust 71%, nss- SO4 = 16% and sea salt 13%. The coarse-particle fraction (CPF) (aerodynamic diameter > 1 μm) of nss SO4= varied from about 21% to 73%, with the highest CPF values associated with African dust events. The CPF nss SO 4= was believed to be a result of the heterogeneous reactions of SO2 (presumably from European sources) with dust particles suspended in the air over North Africa. This study provides the first direct evidence that confirms the importance of dust in sulfate production and resulting the coarse particle sulfate in the tropical Atlantic Ocean region. An important implication is that dust particles may reduce the effectiveness of sulfate aerosol as a radiative forcing agent in many regions where dust events are frequent and where dust concentrations are high. The aerosol scattering coefficient (ASC) measured during this experiment increased by a factor of 1.13 to 1.69 when RH was increased from about 40% to 80%. Through chemical apportioning of ASC, the HGF for sea-salt was found to be 1.8 +/- 0.2, while that of mineral dust was close to unity. This study shows that climate studies must consider the effect of mineral dust not only because of its direct effects on the radiation balance but also because of its

  18. International employees' concerns during serious disease outbreaks and the potential impact on business continuity: Lessons identified from the 2014-15 West African Ebola outbreak.

    PubMed

    Cole, Jennifer; Watkins, Chris

    This paper presents the findings of research carried out into the information-seeking behaviour, and information requirements of a small sample of international workers stationed in West Africa during the Zaire Ebola virus outbreak of 2014-15. The research study under which these results were obtained was part of exploratory research for a PhD focused on the use, and potential uses, of social media platforms during serious disease outbreaks that might be used to inform policy planning for public health and emergency response interventions. Thus, the findings from this study may provide valuable insights to business continuity managers and emergency planners in making future decisions about information exchange and crisis decision-making during future serious disease outbreaks. PMID:26642172

  19. African dust in the Caribbean: chemical, physical and optical properties of transported African dust across the Atlantic: observations from Atmospheric Observatory in Cabezas de San Juan, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Quiñones Rosado, M.; Vallejo, P. M.; Mayol-Bracero, O. L.; Gutiérrez, I.; Ogren, J. A.; Desboeufs, K.; Formenti, P.

    2012-12-01

    We present results on the assessment of aerosols chemical, physical, and optical properties at the atmospheric observatory of Cabezas de San Juan in Fajardo, PR, during the summer 2011, where periods in the presence and absence of dust were studied as part of the project Dust-ATtACk (Dust- Aging and Transport, from Africa to the Caribbean). Dust events were identified through observation and using air-mass back-trajectories, Saharan Air Layer images, measurements of aerosol optical thickness (AOT), in situ scattering and absorption coefficients, and chemical analyses. We focused on results obtained for intense dust events observed in June 22-24 and July 9, 2011. Those events were characterized by higher concentration of coarse particles, higher concentration of metals associated with mineral dust (e.g., Si 3 μg/m3 compared to background concentrations of 0.15 μg/m3), higher scattering and absorption coefficients (up to 100 Mm-1 and 2.5 Mm-1 at 550 and 530 nm, respectively), and AOT (from 0.4 to 0.8) values. The single scattering albedo (SSA) was calculated for the periods of interest for the PM10 and the PM1 mass fractions and plotted against wavelength. For PM10, SSA values ranged from 0.93 to 0.99 and had the same trend reported for dust, with lower SSA values at shorter wavelengths. For PM1, values ranged from 0.85 to 0.98 and more variability was observed in terms of SSA wavelength dependence, likely as species other than dust contribute. Satellite products (e.g., Calipso, Seviri) are used in the attempt to trace these events back to their source region at North Africa.

  20. Dust exposure and pneumoconiosis in a South African pottery. 2. Pneumoconiosis and factors influencing reading of radiological opacities.

    PubMed

    Rees, D; Steinberg, M; Becker, P J; Solomon, A

    1992-07-01

    A cross sectional radiological survey of workers exposed to pottery dust during the manufacture of wall tiles and bathroom fittings was conducted in a South African factory. Roughly one third of workers with 15 or more years of service in high dust sections of the factory had pneumoconiosis. Previously undiagnosed advanced cases, including two with progressive massive fibrosis, were working in dusty occupations. A firm diagnosis of potters' pneumoconiosis was made in 11 of the 358 workers radiographed; all had served more than 10 years suggesting that radiography of workers with more than 10 years service would be a successful case finding strategy in South Africa. A combination of rounded and irregular opacities was the most common radiological finding in the workers with pneumoconiosis (55%). Three readers reported on the chest radiographs, and all found an association between small radiological opacities, which were usually irregular or a combination of irregular and rounded, and exposure to pottery dust. The occurrence of irregular radiological opacities in workers exposed to pottery dust deserves further study. The least experienced reader significantly associated age with small opacities when duration of service (years) was used to measure exposure to dust. Sex was not an important predictor of radiological changes consistent with pneumoconiosis. Breast shadows were not an important cause of false positive readings and participating women did not develop pneumoconiosis after less exposure than men. PMID:1637706

  1. Risk factors associated with occurrence of African swine fever outbreaks in smallholder pig farms in four districts along the Uganda-Kenya border.

    PubMed

    Nantima, Noelina; Ocaido, Michael; Ouma, Emily; Davies, Jocelyn; Dione, Michel; Okoth, Edward; Mugisha, Anthony; Bishop, Richard

    2015-03-01

    A cross-sectional survey was carried out to assess risk factors associated with occurrence of African swine fever (ASF) outbreaks in smallholder pig farms in four districts along Kenya-Uganda border. Information was collected by administering questionnaires to 642 randomly selected pig households in the study area. The study showed that the major risk factors that influenced ASF occurrence were purchase of pigs in the previous year (p < 0.000) and feeding of pigs with swill (p < 0.024). By employing cluster analysis, three clusters of pig production types were identified based on production characteristics that were found to differ significantly between districts. The most vulnerable cluster to ASF was households with the highest reported number of ASF outbreaks and composed of those that practiced free range at least some of the time. The majority of the households in this cluster were from Busia district in Uganda. On the other hand, the least vulnerable cluster to ASF composed of households that had the least number of pig purchases, minimal swill feeding, and less treatment for internal and external parasites. The largest proportion of households in this cluster was from Busia district Kenya. The study recommended the need to sensitize farmers to adopt proper biosecurity practices such as total confinement of pigs, treatment of swill, isolation of newly purchased pigs for at least 2 weeks, and provision of incentives for farmers to report suspected outbreaks to authorities and rapid confirmation of outbreaks. PMID:25616986

  2. Particle size distributions of Trade-Wind African dust measured in the air and after dispersal in water

    NASA Astrophysics Data System (ADS)

    Prospero, J. M.; Custals, L.

    2012-12-01

    the large seasonal changes in particle size characteristics to changes in dust source region; in winter-spring dust sources appear to be most active in the Sahel region of North Africa while in summer the larger Sahara becomes dominant. Measurements of particles on impactor stages confirm that particles are highly agglomerated, most likely as a large core particle serving as the host for smaller particles (rather than massive clumps of smaller particles). It is notable that in Miami during summer dust episodes the measurements of dust size properties are identical to those in Barbados. In other times of year in Miami there is, in effect, no significant dust signature except for greatly increased concentrations of relatively large particles which yield a noisy pattern that suggests a local or regional source. Our results thus far yield African dust size distributions that are broadly consistent with those reported for Greenland ice cores. We seek to identify the possible causes in the observed size shifts, focusing on large dust events, and to relate each event with a specific source region (using remote sensing products) and meteorological conditions.

  3. Overview of the Dust and Biomass-burning Experiment and African Monsoon Multidisciplinary Analysis Special Observing Period-0

    NASA Astrophysics Data System (ADS)

    Haywood, J. M.; Pelon, J.; Formenti, P.; Bharmal, N.; Brooks, M.; Capes, G.; Chazette, P.; Chou, C.; Christopher, S.; Coe, H.; Cuesta, J.; Derimian, Y.; Desboeufs, K.; Greed, G.; Harrison, M.; Heese, B.; Highwood, E. J.; Johnson, B.; Mallet, M.; Marticorena, B.; Marsham, J.; Milton, S.; Myhre, G.; Osborne, S. R.; Parker, D. J.; Rajot, J.-L.; Schulz, M.; Slingo, A.; Tanré, D.; Tulet, P.

    2008-12-01

    The African Monsoon Multidisciplinary Analysis (AMMA) is a major international campaign investigating far-reaching aspects of the African monsoon, climate and the hydrological cycle. A special observing period was established for the dry season (SOP0) with a focus on aerosol and radiation measurements. SOP0 took place during January and February 2006 and involved several ground-based measurement sites across west Africa. These were augmented by aircraft measurements made by the Facility for Airborne Atmospheric Measurements (FAAM) aircraft during the Dust and Biomass-burning Experiment (DABEX), measurements from an ultralight aircraft, and dedicated modeling efforts. We provide an overview of these measurement and modeling studies together with an analysis of the meteorological conditions that determined the aerosol transport and link the results together to provide a balanced synthesis. The biomass burning aerosol was significantly more absorbing than that measured in other areas and, unlike industrial areas, the ratio of excess carbon monoxide to organic carbon was invariant, which may be owing to interaction between the organic carbon and mineral dust aerosol. The mineral dust aerosol in situ filter measurements close to Niamey reveals very little absorption, while other measurements and remote sensing inversions suggest significantly more absorption. The influence of both mineral dust and biomass burning aerosol on the radiation budget is significant throughout the period, implying that meteorological models should include their radiative effects for accurate weather forecasts and climate simulations. Generally, the operational meteorological models that simulate the production and transport of mineral dust show skill at lead times of 5 days or more. Climate models that need to accurately simulate the vertical profiles of both anthropogenic and natural aerosols to accurately represent the direct and indirect effects of aerosols appear to do a reasonable job

  4. Soil genesis on the island of Bermuda in the Quaternary: the importance of African dust transport and deposition

    USGS Publications Warehouse

    Muhs, Daniel R.; Budahn, James R.; Prospero, Joseph M.; Skipp, Gary; Herwitz, Stanley R.

    2012-01-01

    The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (N/YbN, GdN/YbN that can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past –500 ka.

  5. Saharan Dust, Transport Processes, and Possible Impacts on Hurricane Activities

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, K. M.

    2010-01-01

    In this paper, we present observational evidence of significant relationships between Saharan dust outbreak, and African Easterly wave activities and hurricane activities. We found two dominant paths of transport of Saharan dust: a northern path, centered at 25degN associated with eastward propagating 6-19 days waves over northern Africa, and a southern path centered at 15degN, associated with the AEW, and the Atlantic ITCZ. Seasons with stronger dust outbreak from the southern path are associated with a drier atmosphere over the Maximum Development Region (MDR) and reduction in tropical cyclone and hurricane activities in the MDR. Seasons with stronger outbreak from the northern path are associated with a cooler N. Atlantic, and suppressed hurricane in the western Atlantic basin.

  6. The Influence of African Dust on Air Quality in the Caribbean Basin: An Integrated Analysis of Satellite Retrievals, Ground Observations, and Model Simulations

    NASA Astrophysics Data System (ADS)

    Yu, H.; Prospero, J. M.; Chin, M.; Randles, C. A.; da Silva, A.; Bian, H.

    2015-12-01

    Long-term surface measurements in several locations extending from northeastern coast of South America to Miami in Florida have shown that African dust arrives in the Greater Caribbean Basin throughout a year. This long-range transported dust frequently elevates the level of particulate matter (PM) above the WHO guideline for PM10, which raises a concern of possible adverse impact of African dust on human health in the region. There is also concern about how future climate change might affect dust transport and its influence on regional air quality. In this presentation we provide a comprehensive characterization of the influence of African dust on air quality in the Caribbean Basin via integrating the ground observations with satellite retrievals and model simulations. The ground observations are used to validate and evaluate satellite retrievals and model simulations of dust, while satellite measurements and model simulations are used to extend spatial coverage of the ground observations. An analysis of CALIPSO lidar measurements of three-dimensional distribution of aerosols over 2007-2014 yields altitude-resolved dust mass flux into the region. On a basis of 8-year average and integration over the latitude zone of 0°-30°N, a total of 76 Tg dust is imported to the air above the Greater Caribbean Basin, of which 34 Tg (or 45%) is within the lowest 1 km layer and most relevant to air quality concern. The seasonal and interannual variations of the dust import are well correlated with ground observations of dust in Cayenne, Barbados, Puerto Rico, and Miami. We will also show comparisons of the size-resolved dust amount from both NASA GEOS-5 aerosol simulation and MERRA-2 aerosol reanalysis (i.e., column aerosol loading being constrained by satellite measurements of radiance at the top of atmosphere) with the ground observations and satellite measurement.

  7. Columnar Aerosol Single-Scattering Albedo and Phase Function Retrieved from Sky Radiance Over the Ocean: Measurements of African Dust

    NASA Technical Reports Server (NTRS)

    Cattrall, Christopher; Carder, Kendall L.; Gordon, Howard R.

    2001-01-01

    The single-scattering albedo and phase function of African mineral dust are retrieved from ground-based measurements of sky radiance collected in the Florida Keys. The retrieval algorithm employs the radiative transfer equation to solve by iteration for these two properties which best reproduce the observed sky radiance using an assumed aerosol vertical structure and measured aerosol optical depth. Thus, no assumptions regarding particle size, shape, or composition are required. The single-scattering albedo, presented at fourteen wavelengths between 380 and 870 nm, displays a spectral shape expected of iron-bearing minerals but is much higher than current dust models allow. This indicates the absorption of light by mineral dust is significantly overestimated in climate studies. Uncertainty in the retrieved albedo is less than 0.02 due to the small uncertainty in the solar-reflectance-based calibration (12.2%) method employed. The phase function retrieved at 860 nm is very robust under simulations of expected experimental errors, indicating retrieved phase functions at this wavelength may be confidently used to describe aerosol scattering characteristics. The phase function retrieved at 443 nm is very sensitive to expected experimental errors and should not be used to describe aerosol scattering. Radiative forcing by aerosol is the greatest source of uncertainty in current climate models. These results will help reduce uncertainty in the absorption of light by mineral dust. Assessment of the radiative impact of aerosol species is a key component to NASA's Earth System Enterprise.

  8. Cross-shift peak expiratory flow changes are unassociated with respirable coal dust exposure among South African coal miners

    SciTech Connect

    Naidoo, R.N.; Robins, T.G.; Becklake, M.; Seixas, N.; Thompson, M.L.

    2007-12-15

    he objectives of this study were to determine whether cross-shift changes in peak expiratory flow rate (PEFR) were related to respirable dust exposure in South African coalminers. Fifty workers were randomly selected from a cohort of 684 miners from 3 bituminous coal mines in Mpumalanga, South Africa. Peak expiratory efforts were measured prior to the commencement of the shift, and at the end of the shift on at least two occasions separated by at least 2 weeks, with full shift personal dust sampling being conducted on each occasion for each participant. Interviews were conducted, work histories were obtained and cumulative exposure estimates were constructed. Regression models examined the associations of cross-shift changes in PEFR with current and cumulative exposure, controlling for shift, smoking and past history of tuberculosis. There were marginal differences in cross-shift PEFR (ranging from 0.1 to 2 L/min). Linear regression analyses showed no association between cross-shift change in PEFR and current or cumulative exposure. The specific shift worked by participants in the study showed no effect. Our study showed no association between current respirable dust exposure and cross-shift changes in PEFR. There was a non-significant protective effect of cumulative dust exposure on the outcome, suggesting the presence of a 'healthy worker survivor effect' in this data.

  9. Soil genesis on the island of Bermuda in the Quaternary: The importance of African dust transport and deposition

    NASA Astrophysics Data System (ADS)

    Muhs, Daniel R.; Budahn, James R.; Prospero, Joseph M.; Skipp, Gary; Herwitz, Stanley R.

    2012-09-01

    The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (<20μm) component of distal loess from the lower Mississippi River Valley, and LRT dust from Africa. These parent materials can be characterized geochemically using trace elements that are immobile in the soil-forming environment. Results indicate that local volcanic bedrock on Bermuda has Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbNthat can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past ˜500 ka.

  10. Size distribution and optical properties of African mineral dust after intercontinental transport

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Formenti, Paola; Desboeufs, Karine; Chevaillier, Servanne; Triquet, Sylvain; Maillé, Michel; Cazaunau, Mathieu; Laurent, Benoit; Mayol-Bracero, Olga L.; Vallejo, Pamela; Quiñones, Mariana; Gutierrez-Molina, Ian E.; Cassola, Federico; Prati, Paolo; Andrews, Elisabeth; Ogren, John

    2016-06-01

    The transatlantic transport of mineral dust from Africa is a persistent atmospheric phenomenon, clue for understanding the impacts of dust at the global scale. As part of the DUST Aging and Transport from Africa to the Caribbean (Dust-ATTACk) intensive field campaign, the size distribution and optical properties of mineral dust were measured in June-July 2012 on the east coast of Puerto Rico, more than 5000 km from the west coast of Africa. During the recorded dust events, the PM10 (particulate matter 10 micrometers or less in diameter) concentrations increased from 20 to 70 µg m-3. Remote sensing observations and modeling analysis were used to identify the main source regions, which were found in the Western Sahara, Mauritania, Algeria, Niger, and Mali. The microphysical and optical properties of the dust plumes were almost independent of origin. The size distribution of mineral dust after long-range transport may have modal diameters similar to those on the eastern side of the Atlantic short time after emission, possibly depending on height of transport. Additional submicron particles of anthropogenic absorbing aerosols (likely from regional marine traffic activities) can be mixed within the dust plumes, without affecting in a significant way the PM10 absorption properties of dust observed in Puerto Rico. The Dust-ATTACk experimental data set may be useful for modeling the direct radiative effect of dust. For accurate representation of dust optical properties over the Atlantic remote marine region, we recommend mass extinction efficiency (MEE) and single-scattering albedo values in the range 1.1-1.5 m2 g-1 and 0.97-0.98, respectively, for visible wavelengths.

  11. Semidirect Dynamical and Radiative Impact of North African Dust Transport on Lower Tropospheric Clouds over the Subtropical North Atlantic in CESM 1.0

    SciTech Connect

    DeFlorio, Mike; Ghan, Steven J.; Singh, Balwinder; Miller, Arthur J.; Cayan, Dan; Russell, Lynn M.; Somerville, Richard C.

    2014-07-16

    This study uses a century length pre-industrial climate simulation by the Community Earth System Model (CESM 1.0) to explore statistical relationships between dust, clouds and atmospheric circulation, and to suggest a dynamical, rather than microphysical, mechanism linking subtropical North Atlantic lower tropospheric cloud cover with North African dust transport. The length of the run allows us to account for interannual variability of dust emissions and transport downstream of North Africa in the model. CESM’s mean climatology and probability distribution of aerosol optical depth in this region agrees well with available AERONET observations. In addition, CESM shows strong seasonal cycles of dust burden and lower tropospheric cloud fraction, with maximum values occurring during boreal summer, when a strong correlation between these two variables exists downstream of North Africa over the subtropical North Atlantic. Calculations of Estimated Inversion Strength (EIS) and composites of EIS on high and low downstream North Africa dust months during boreal summer reveal that dust is likely increasing inversion strength over this region due to both solar absorption and reflection. We find no evidence for a microphysical link between dust and lower tropospheric clouds in this region. These results yield new insight over an extensive period of time into the complex relationship between North African dust and lower tropospheric clouds over the open ocean, which has previously been hindered by spatiotemporal constraints of observations. Our findings lay a framework for future analyses using sub-monthly data over regions with different underlying dynamics.

  12. Does the long-range transport of African mineral dust across the Atlantic enhance their hygroscopicity?

    NASA Astrophysics Data System (ADS)

    Denjean, Cyrielle; Caquineau, Sandrine; Desboeufs, Karine; Laurent, Benoit; Quiñones Rosado, Mariana; Vallejo, Pamela; Mayol-Bracero, Olga; Formenti, Paola

    2015-04-01

    Influence of mineral dust on radiation balance is largely dependent on their ability to interact with water. While fresh mineral dusts are highly hydrophobic, various transformation processes (coagulation, heterogeneous chemical reaction) can modify the dust physical and chemical properties during long-range transport, which, in turn, can change the dust hygroscopic properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of dust hygroscopic properties, and their temporal evolution during long-range transport. We present the first direct surface measurements of the hygroscopicity of Saharan dust after long-range transport over the Atlantic Ocean, their relationship with chemical composition, their influence on particle size and shape and implications for optical properties. Particles were collected during the DUST Aging and TransporT from Africa to the Caribbean (Dust-AttaCk) campaign at the Cape San Juan Puerto Rico station in June-July 2012. Environmental scanning electron microscopy (ESEM) was used to analyze the size, shape, chemical composition and hygroscopic properties of individual particles. At different levels of concentrations in summertime, the coarse mode of atmospheric aerosols in Puerto Rico is dominated by Saharan mineral dust. Most of aged dust particles survived atmospheric transport intact with no observed internal mixture with other species and did not show hygroscopic growth up to 94% relative humidity. This is certainly due to the fact that in summertime dust is mostly transported above the marine boundary layer. A minor portion of mineral dust (approximately 19-28% by number) were involved in atmospheric heterogeneous reactions with acidic gases (likely SO2 and HCl) and sea salt aggregation. While sulfate- and chloride-coated dust remained extremely hydrophobic, dust particles in internal mixing with NaCl underwent profound changes in their hygroscopicity, therefore in size and shape. We

  13. How much North African dust emission is associated with breakdowns of nocturnal low-level jets?

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Schepanski, K.; Heinold, B.; Knippertz, P.; Tegen, I.

    2013-12-01

    Mineral dust aerosol has important impacts on atmospheric radiation transfer, optical properties and precipitability of clouds, as well as human health and eco-systems. Time, location and amount of dust emission are key factors for simulating the atmospheric life cycle of dust and its effects accurately. Dust emission is a non-linear function of surface properties, and the momentum transfer from the atmosphere to the Earth's surface. A phenomenon capable of mobilizing dust is the Nocturnal Low-Level Jet (NLLJ), a wind speed maximum at night caused by air accelerating due to reduced dynamical friction in the nocturnal boundary layer. Momentum from the NLLJ is transferred downwards by turbulence, predominantly during the following morning when surface heating erodes the nocturnal temperature inversion. While this breakdown of NLLJs has been suggested to be a main driver for dust storms in North Africa, a quantitative investigation based on analysis data is lacking. As part of the European Research Council funded 'Desert Storms' project, this work presents the first statistical analysis of the importance of NLLJs for the mineral dust amount emitted in North Africa. A new automated detection algorithm for NLLJs has been developed for analyzing the spatio-temporal characteristics and associated mineral dust emission amounts. The algorithm is applied to the European Centre for Medium-Range Weather Forecasts ERA-Interim re-analysis for 1979-2010. Near-surface wind speed and soil moisture from ERA-interim drive an off-line dust model for calculating associated dust emission fluxes. Annually and spatially averaged, NLLJs form in 29 % of the nights in North Africa. The areal distribution of NLLJs highlights their frequent occurrence along the margins of the Saharan heat-low in summer, and in regions affected by mountain channeling like the Bodélé Depression, Chad, predominantly in winter. In these seasonally varying hotspots NLLJs are identified in 40-80 % of the nights

  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

    , Katsouyanni K, Kelessis AG, Linares C, Marchesi S, Medina S, Pandolfi P, Pérez N, Querol X, Randi G, Ranzi A, Tobias A, Forastiere F, MED-PARTICLES Study Group. 2016. Desert dust outbreaks in Southern Europe: contribution to daily PM10 concentrations and short-term associations with mortality and hospital admissions. Environ Health Perspect 124:413–419; http://dx.doi.org/10.1289/ehp.1409164 PMID:26219103

  15. Variations in the size distribution of non-sea-salt sulfate aerosol in the marine boundary layer at Barbados: Impact of African dust

    NASA Astrophysics Data System (ADS)

    Li-Jones, X.; Prospero, J. M.

    1998-01-01

    Four African mineral dust episodes occurred during a program of daily aerosol measurements at Barbados (13°15'N, 59°30'W) in April 1994. Non-sea-salt sulfate (nss SO4=) and dust were highly correlated (r2 = 0.93) and ranged from 0.5 to 4.2 μg m-3 and 0.9 to 257 μg m-3, respectively. Day-to-day variations in the size distributions of mineral dust and sea salt were relatively small. However, the coarse-particle (aerodynamic diameter > 1 μm) fraction (CPF) of nss SO4= varied substantially, from 21% to 73%. The highest CPF SO4= values were associated with dust events; the lowest CPF was associated with the air mass from the central North Atlantic when the dust concentration was lowest, 0.9 μg m-3. We suggest that large CPF SO4= values are a consequence of SO2 in European pollutants that heterogeneously react with the suspended dust over North Africa. Nonetheless, the association of pollutants and dust does not always result in a large CPF; low CPF values suggest that SO2 may have been oxidized to SO4= prior to mixing with dust-laden air. On those days when dust and pollution concentrations were low, the dominant source of nss SO4= was ascribed to oceanic dimethylsulfide (DMS) and the CPF remained close to 20%. Because such large variations can occur in the particle size distribution of nss SO4= in association with dust events, the role of mineral dust on nss SO4= size must be taken into account when estimating the impact of nss SO4= on radiation transfer in the atmosphere.

  16. Study of African Dust with Multi-Wavelength Raman Lidar During "Shadow" Campaign in Senegal

    NASA Astrophysics Data System (ADS)

    Veselovskii, Igor; Goloub, Philippe; Podvin, Thierry; Bovchaliuk, Valentyn; Tanre, Didier; Derimian, Yevgeny; Korenskiy, Mikhail; Dubovik, Oleg

    2016-06-01

    West Africa and the adjacent oceanic regions are very important locations for studying dust properties and their influence on weather and climate. The SHADOW (Study of SaHAran Dust Over West Africa) campaign is performing a multi-scale and multi-laboratory study of aerosol properties and dynamics using a set of in situ and remote sensing instruments at an observation site located at IRD (Institute for Research and Development) Center, Mbour, Senegal (14°N, 17°W). In this paper, we present the results of lidar measurements performed during the first phase of SHADOW which occurred in March-April, 2015. The multiwavelength Mie-Raman lidar acquired 3β+2α+1δ measurements during this period. This set of measurements has permitted particle intensive properties such as extinction and backscattering Ångström exponents (BAE) for 355/532 nm wavelengths corresponding lidar ratios and depolarization ratio at 532 nm to be determined. The backscattering Ångström exponent during the dust episodes decreased to ~-0.7, while the extinction Ångström exponent though being negative, was greater than -0.2. Low values of BAE can likely be explained by an increase in the imaginary part of the dust refractive index at 355 nm compared to 532 nm.

  17. The fertilizing role of African dust in the Amazon rainforest: A first multiyear assessment based on data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations

    NASA Astrophysics Data System (ADS)

    Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Remer, Lorraine A.; Prospero, Joseph M.; Omar, Ali; Winker, David; Yang, Yuekui; Zhang, Yan; Zhang, Zhibo; Zhao, Chun

    2015-03-01

    The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three-dimensional (3-D) aerosol measurements over 2007-2013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7 year average of dust deposition into the Amazon Basin is estimated to be 28 (8-48) Tg a-1 or 29 (8-50) kg ha-1 a-1. The dust deposition shows significant interannual variation that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multiyear mean estimate of dust deposition matches better with estimates from in situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3-D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.006-0.037) Tg P of phosphorus per year, equivalent to 23 (7-39) g P ha-1 a-1 to fertilize the Amazon rainforest. This out-of-basin phosphorus input is comparable to the hydrological loss of phosphorus from the basin, suggesting an important role of African dust in preventing phosphorus depletion on timescales of decades to centuries.

  18. The Fertilizing Role of African Dust in the Amazon Rainforest. A First Multiyear Assessment Based on Data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations

    SciTech Connect

    Yu, Hongbin; Chin, Mian; Yuan, Tianle; Bian, Huisheng; Remer, L. A.; Prospero, J.; Omar, Ali; Winker, D.; Yang, Yuekui; Zhang, Yan; Zhang, Zhibo; Zhao, Chun

    2015-03-18

    The productivity of the Amazon rainforest is constrained by the availability of nutrients, in particular phosphorus (P). Deposition of long-range transported African dust is recognized as a potentially important but poorly quantified source of phosphorus. This study provides a first multiyear satellite-based estimate of dust deposition into the Amazon Basin using three dimensional (3D) aerosol measurements over 2007-2013 from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The 7-year average of dust deposition into the Amazon Basin is estimated to be 28 (8~48) Tg a-1 or 29 (8~50) kg ha-1 a-1. The dust deposition shows significant interannual variation that is negatively correlated with the prior-year rainfall in the Sahel. The CALIOP-based multi-year mean estimate of dust deposition matches better with estimates from in-situ measurements and model simulations than a previous satellite-based estimate does. The closer agreement benefits from a more realistic geographic definition of the Amazon Basin and inclusion of meridional dust transport calculation in addition to the 3D nature of CALIOP aerosol measurements. The imported dust could provide about 0.022 (0.006~0.037) Tg P of phosphorus per year, equivalent to 23 (7~39) g P ha-1 a-1 to fertilize the Amazon rainforest. This out-of-Basin P input is comparable to the hydrological loss of P from the Basin, suggesting an important role of African dust in preventing phosphorus depletion on time scales of decades to centuries.

  19. Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDE

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Redemann, Jens; Russell, Philip; Schmid, Beat; Reid, Jeff; Pilewskie, Peter; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident

  20. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, A.; Prospero, J. M.; Sharifi, A.

    2014-12-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  1. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, Ali; Prospero, Joseph; Sharifi, Arash

    2015-04-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  2. Aerosol interactions with African/Atlantic climate dynamics

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.

    2014-07-01

    Mechanistic relationships exist between variability of dust in the oceanic Saharan air layer (OSAL) and transient changes in the dynamics of Western Africa and the tropical Atlantic Ocean. This study provides evidence of possible interactions between dust in the OSAL region and African easterly jet-African easterly wave (AEJ-AEW) system in the climatology of boreal summer, when easterly wave activity peaks. Synoptic-scale changes in instability and precipitation in the African/Atlantic intertropical convergence zone are correlated with enhanced aerosol optical depth (AOD) in the OSAL region in response to anomalous 3D overturning circulations and upstream/downstream thermal anomalies at above and below the mean-AEJ level. Upstream and downstream anomalies are referred to the daily thermal/dynamical changes over the West African monsoon region and the Eastern Atlantic Ocean, respectively. Our hypothesis is that AOD in the OSAL is positively correlated with the downstream AEWs and negatively correlated with the upstream waves from climatological perspective. The similarity between the 3D pattern of thermal/dynamical anomalies correlated with dust outbreaks and those of AEWs provides a mechanism for dust radiative heating in the atmosphere to reinforce AEW activity. We proposed that the interactions of OSAL dust with regional climate mainly occur through coupling of dust with the AEWs.

  3. Wild and Domestic Pig Interactions at the Wildlife-Livestock Interface of Murchison Falls National Park, Uganda, and the Potential Association with African Swine Fever Outbreaks.

    PubMed

    Kukielka, Esther A; Jori, Ferran; Martínez-López, Beatriz; Chenais, Erika; Masembe, Charles; Chavernac, David; Ståhl, Karl

    2016-01-01

    Bushpigs (BPs) (Potamochoerus larvatus) and warthogs (WHs) (Phacochoerus africanus), which are widely distributed in Eastern Africa, are likely to cohabitate in the same environment with domestic pigs (DPs), facilitating the transmission of shared pathogens. However, potential interactions between BP, WH, and DP, and the resulting potential circulation of infectious diseases have rarely been investigated in Africa to date. In order to understand the dynamics of such interactions and the potential influence of human behavior and husbandry practices on them, individual interviews (n = 233) and participatory rural appraisals (n = 11) were carried out among Ugandan pig farmers at the edge of Murchison Falls National Park, northern Uganda. In addition, as an example of possible implications of wild and DP interactions, non-linear multivariate analysis (multiple correspondence analyses) was used to investigate the potential association between the aforementioned factors (interactions and human behavior and practices) and farmer reported African swine fever (ASF) outbreaks. No direct interactions between wild pigs (WPs) and DP were reported in our study area. However, indirect interactions were described by 83 (35.6%) of the participants and were identified to be more common at water sources during the dry season. Equally, eight (3.4%) farmers declared exposing their DP to raw hunting leftovers of WPs. The exploratory analysis performed suggested possible associations between the farmer reported ASF outbreaks and indirect interactions, free-range housing systems, dry season, and having a WH burrow less than 3 km from the household. Our study was useful to gather local knowledge and to identify knowledge gaps about potential interactions between wild and DP in this area. This information could be useful to facilitate the design of future observational studies to better understand the potential transmission of pathogens between wild and DPs. PMID:27148545

  4. Wild and Domestic Pig Interactions at the Wildlife–Livestock Interface of Murchison Falls National Park, Uganda, and the Potential Association with African Swine Fever Outbreaks

    PubMed Central

    Kukielka, Esther A.; Jori, Ferran; Martínez-López, Beatriz; Chenais, Erika; Masembe, Charles; Chavernac, David; Ståhl, Karl

    2016-01-01

    Bushpigs (BPs) (Potamochoerus larvatus) and warthogs (WHs) (Phacochoerus africanus), which are widely distributed in Eastern Africa, are likely to cohabitate in the same environment with domestic pigs (DPs), facilitating the transmission of shared pathogens. However, potential interactions between BP, WH, and DP, and the resulting potential circulation of infectious diseases have rarely been investigated in Africa to date. In order to understand the dynamics of such interactions and the potential influence of human behavior and husbandry practices on them, individual interviews (n = 233) and participatory rural appraisals (n = 11) were carried out among Ugandan pig farmers at the edge of Murchison Falls National Park, northern Uganda. In addition, as an example of possible implications of wild and DP interactions, non-linear multivariate analysis (multiple correspondence analyses) was used to investigate the potential association between the aforementioned factors (interactions and human behavior and practices) and farmer reported African swine fever (ASF) outbreaks. No direct interactions between wild pigs (WPs) and DP were reported in our study area. However, indirect interactions were described by 83 (35.6%) of the participants and were identified to be more common at water sources during the dry season. Equally, eight (3.4%) farmers declared exposing their DP to raw hunting leftovers of WPs. The exploratory analysis performed suggested possible associations between the farmer reported ASF outbreaks and indirect interactions, free-range housing systems, dry season, and having a WH burrow less than 3 km from the household. Our study was useful to gather local knowledge and to identify knowledge gaps about potential interactions between wild and DP in this area. This information could be useful to facilitate the design of future observational studies to better understand the potential transmission of pathogens between wild and DPs. PMID:27148545

  5. African dust phosphorus fertilizing the Amazon and the Atlantic Ocean is derived from marine sediments and igneous rocks - no indication for Bodélé diatomite contribution

    NASA Astrophysics Data System (ADS)

    Gross, Avner; Castido, Danilo; Pio, Casimero; Angert, Alon

    2013-04-01

    signatures. The diatomite in the Bodélé depression have lower P concentrations (550-900 µg P g/dust) and fall off the mixing line describe by our samples. These findings implies that the bio-available P delivered by dust from West Africa to the Central Atlantic Ocean and later to the Amazon basin is derived from a mixture of igneous origin and marine sedimentary origin, and that in contrast to previous claims, the Bodélé diatomite is not a major dust-P source. In addition, we found that African dust-P concentrations are between 2 folds to 10 folds higher then generally accounted for in modeling studies.

  6. The role of African dust in the formation of Quaternary soils on Mallorca, Spain and implications for the genesis of Red Mediterranean soils

    NASA Astrophysics Data System (ADS)

    Muhs, Daniel R.; Budahn, James; Avila, Anna; Skipp, Gary; Freeman, Joshua; Patterson, DeAnna

    2010-09-01

    African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation, immobile element ratios in the soils require an external source. However, Zr/Hf, La/Yb, Cr/Sc and Th/Ta values in the soils fall within the range of values for these element ratios in African dust collected on Barbados and mainland Spain. We conclude that the silicate fractions of terra rossa soils on Mallorca are derived mainly, though not wholly, from far-traveled African dust, and this process may explain the origin of other terra rossa soils found in southern Europe.

  7. The role of African dust in the formation of Quaternary soils on Mallorca, Spain and implications for the genesis of Red Mediterranean soils

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.; Avila, A.; Skipp, G.; Freeman, J.; Patterson, D.

    2010-01-01

    African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation, immobile element ratios in the soils require an external source. However, Zr/Hf, La/Yb, Cr/Sc and Th/Ta values in the soils fall within the range of values for these element ratios in African dust collected on Barbados and mainland Spain. We conclude that the silicate fractions of terra rossa soils on Mallorca are derived mainly, though not wholly, from far-traveled African dust, and this process may explain the origin of other terra rossa soils found in southern Europe. ?? 2010.

  8. Linking Endotoxins, African Dust PM10 and Asthma in an Urban and Rural Environment of Puerto Rico

    PubMed Central

    Ortiz-Martínez, Mario G.; Rodríguez-Cotto, Rosa I.; Ortiz-Rivera, Mónica A.; Pluguez-Turull, Cedric W.; Jiménez-Vélez, Braulio D.

    2015-01-01

    African Dust Events (ADE) are a seasonal phenomenon that has been suggested to exacerbate respiratory and proinflammatory diseases in Puerto Rico (PR). Increases in PM10 concentration and the effects of biological endotoxins (ENX) are critical factors to consider during these storms. ENX promote proinflammatory responses in lungs of susceptible individuals through activation of the Toll-like receptors (TLR2/4) signaling pathways. The objective of the study was to evaluate the toxicological and proinflammatory responses stimulated by ADE PM10 ENX reaching PR using human bronchial epithelial cells. PM10 organic extracts from a rural and urban site in PR (March 2004) were obtained from ADE and non-ADE and compared. A retrospective data analysis (PM10 concentration, aerosol images, and pediatric asthma claims) was performed from 2000 to 2012 with particular emphasis in 2004 to classify PM samples. Urban extracts were highly toxic, proinflammatory (IL-6/IL-8 secretion), and induced higher TLR4 expression and NF-κB activation compared to rural extracts. ENX were found to contribute to cytotoxicity and inflammatory responses provoked by urban ADE PM10 exposure suggesting a synergistic potency of local and natural ENX incoming from ADE. The contribution of ADE PM10 ENX is valuable in order to understand interactions and action mechanisms of airborne pollutants as asthma triggers in PR. PMID:26681839

  9. Occurrence, distribution and health risk from polycyclic aromatic compounds (PAHs, oxygenated-PAHs and azaarenes) in street dust from a major West African Metropolis.

    PubMed

    Bandowe, Benjamin A Musa; Nkansah, Marian Asantewah

    2016-05-15

    Scientific evidence suggests that the burden of disease on urban residents of sub-Saharan African Countries is increasing, partly as a result of exposure to elevated concentrations of toxic environmental chemicals. However, characterization of the levels, composition pattern and sources of polycyclic aromatic compounds (PACs) in environmental samples from African cities is still lacking. This study measured the PAHs, oxygenated-PAHs (OPAHs) and azaarene (AZAs) content of street dusts collected from Kumasi, Ghana (a major metropolis located in the tropical forest zone of West Africa). The ∑Alkyl+parent-PAHs, ∑OPAHs and ∑AZAs concentration in street dust averaged 2570ngg(-1) (range: 181-7600ngg(-1)), 833ngg(-1) (57-4200ngg(-1)) and 73ngg(-1) (3.3-240ngg(-1)), respectively. The concentrations of ∑Alkyl+parent-PAHs were strongly correlated (n=25) with ∑OPAHs (r=0.96, p<0.01) and ∑AZAs (r=0.94, p<0.01). The ∑OPAHs concentrations were also strongly correlated with ∑AZAs (r=0.91, p<0.01). Concentrations of individual PAHs in these street dusts were enriched at between 12 and 836 compared to their average concentrations in background soils from same city, demonstrating the high influence of traffic emissions. Several individual OPAHs and AZAs had higher concentrations than their related and often monitored parent-PAHs. The estimated incremental lifetime cancer risks due to the parent-PAHs in street dusts was >10(-6) indicating high risk of contracting cancer from exposure to street dust from Kumasi. The contribution of OPAHs, AZAs, and alkyl-PAHs in street dust to cancer risk could not be quantified because of lack of toxicity equivalency factors for these compounds; however this could be significant because of their high concentration and known higher toxicity of some polar PACs and alkyl-PAHs than their related parent-PAHs. PMID:26930316

  10. Global Health Security: The Lessons from the West African Ebola Virus Disease Epidemic and MERS Outbreak in the Republic of Korea.

    PubMed

    Ghsa Preparation Task Force Team

    2015-12-01

    The Ebola virus disease outbreak in West Africa and the Middle East Respiratory Syndrome outbreak in the Republic of Korea have given huge impacts in different aspects. Health security is no more a new coinage. Global health security became more realistic in its practical application. In the perspective of global health, it will be helpful to peruse lessons learned from the Ebola outbreak in West Africa and MERS outbreak in Korea. PMID:27429901

  11. Do Cloud Properties in a Puerto Rican Tropical Montane Cloud Forest Depend on Occurrence of Long-Range Transported African Dust?

    NASA Astrophysics Data System (ADS)

    Spiegel, Johanna K.; Buchmann, Nina; Mayol-Bracero, Olga L.; Cuadra-Rodriguez, Luis A.; Valle Díaz, Carlos J.; Prather, Kimberly A.; Mertes, Stephan; Eugster, Werner

    2014-09-01

    We investigated cloud properties of warm clouds in a tropical montane cloud forest at Pico del Este (1,051 m a.s.l.) in the northeastern part of Puerto Rico to address the question of whether cloud properties in the Caribbean could potentially be affected by African dust transported across the Atlantic Ocean. We analyzed data collected during 12 days in July 2011. Cloud droplet size spectra were measured using the FM-100 fog droplet spectrometer that measured droplet size distributions in the range from 2 to 49 µm, primarily during fog events. The droplet size spectra revealed a bimodal structure, with the first peak ( D < 6 µm) being more pronounced in terms of droplet number concentrations, whereas the second peak (10 µm < D < 20 µm) was found to be the one relevant for total liquid water content (LWC) of the cloud. We identified three major clusters of characteristic droplet size spectra by means of hierarchical clustering. All clusters differed significantly from each other in droplet number concentration (), effective diameter (ED), and median volume diameter (MVD). For the cluster comprising the largest droplets and the lowest droplet number concentrations, we found evidence of inhomogeneous mixing in the cloud. Contrastingly, the other two clusters revealed microphysical behavior, which could be expected under homogeneous mixing conditions. For those conditions, an increase in cloud condensation nuclei—e.g., from processed African dust transported to the site—is supposed to lead to an increased droplet concentration. In fact, one of these two clusters showed a clear shift of cloud droplet size spectra towards smaller droplet diameters. Since this cluster occurred during periods with strong evidence for the presence of long-range transported African dust, we hypothesize a link between the observed dust episodes and cloud characteristics in the Caribbean at our site, which is similar to the anthropogenic aerosol indirect effect.

  12. Knowledge and behavior in an animal disease outbreak - Evidence from the item count technique in a case of African swine fever in Madagascar.

    PubMed

    Randrianantoandro, Tiana N; Kono, Hiroichi; Kubota, Satoko

    2015-03-01

    Pig production in Madagascar is not sufficient for domestic consumption. Unfortunately, African swine fever (ASF), which is a severe disease, is endemic in Madagascar and constitutes a constant threat for farmers. Therefore, ASF must be eradicated in order to guarantee the development of pig production. One of the main strategies in controlling ASF is stamping out which requires the farmers' collaboration in reporting cases or suspected cases. The objective of this study was to estimate the proportion of farmers who knowingly sell ASF-infected meat without reporting. Since selling ASF-infected meat is prohibited by the government, we used the item count technique (ICT), an indirect questioning technique appropriate for measuring the proportion of people engaged in sensitive behavior, for one subsample, while another subsample was asked directly whether they sell ASF-infected meat. Based on the ICT, approximately 73.2% of farmers who have experienced ASF sell the ASF-infected meat. This estimate was not statistically different from that obtained by direct questioning. In the 28% of interviewed farmers who believe ASF can affect humans, the ICT yielded a higher estimate than did direct questioning, indicating that pig farmers who sell ASF-infected meat hide that fact because of their belief that infected meat might harm human consumers, not because of the law. The ICT was thus a suitable technique to address the problem of sensitive behavior. In the case of ASF outbreaks, the Malagasy government should enforce the law more strictly and provide compensation as incentive for reporting cases. PMID:25591977

  13. Assessment of African Swine Fever Diagnostic Techniques as a Response to the Epidemic Outbreaks in Eastern European Union Countries: How To Improve Surveillance and Control Programs

    PubMed Central

    Nieto, R.; Soler, A.; Pelayo, V.; Fernández-Pinero, J.; Markowska-Daniel, I.; Pridotkas, G.; Nurmoja, I.; Granta, R.; Simón, A.; Pérez, C.; Martín, E.; Fernández-Pacheco, P.; Arias, M.

    2015-01-01

    This study represents a complete comparative analysis of the most widely used African swine fever (ASF) diagnostic techniques in the European Union (EU) using field and experimental samples from animals infected with genotype II ASF virus (ASFV) isolates circulating in Europe. To detect ASFV, three different PCRs were evaluated in parallel using 785 field and experimental samples. The results showed almost perfect agreement between the Universal ProbeLibrary (UPL-PCR) and the real-time (κ = 0.94 [95% confidence interval {CI}, 0.91 to 0.97]) and conventional (κ = 0.88 [95% CI, 0.83 to 0.92]) World Organisation for Animal Health (OIE)-prescribed PCRs. The UPL-PCR had greater diagnostic sensitivity for detecting survivors and allows earlier detection of the disease. Compared to the commercial antigen enzyme-linked immunosorbent assay (ELISA), good-to-moderate agreement (κ = 0.67 [95% CI, 0.58 to 0.76]) was obtained, with a sensitivity of 77.2% in the commercial test. For ASF antibody detection, five serological methods were tested, including three commercial ELISAs, the OIE-ELISA, and the confirmatory immunoperoxidase test (IPT). Greater sensitivity was obtained with the IPT than with the ELISAs, since the IPT was able to detect ASF antibodies at an earlier point in the serological response, when few antibodies are present. The analysis of the exudate tissues from dead wild boars showed that IPT might be a useful serological tool for determining whether or not animals had been exposed to virus infection, regardless of whether antibodies were present. In conclusion, the UPL-PCR in combination with the IPT was the most trustworthy method for detecting ASF during the epidemic outbreaks affecting EU countries in 2014. The use of the most appropriate diagnostic tools is critical when implementing effective control programs. PMID:26041901

  14. Assessment of the potential for international dissemination of Ebola virus via commercial air travel during the 2014 west African outbreak

    PubMed Central

    Bogoch, Isaac I; Creatore, Maria I; Cetron, Martin S; Brownstein, John S; Pesik, Nicki; Miniota, Jennifer; Tam, Theresa; Hu, Wei; Nicolucci, Adriano; Ahmed, Saad; Yoon, James W; Berry, Isha; Hay, Simon I; Anema, Aranka; Tatem, Andrew J; MacFadden, Derek; German, Matthew; Khan, Kamran

    2015-01-01

    Summary Background The WHO declared the 2014 west African Ebola epidemic a public health emergency of international concern in view of its potential for further international spread. Decision makers worldwide are in need of empirical data to inform and implement emergency response measures. Our aim was to assess the potential for Ebola virus to spread across international borders via commercial air travel and assess the relative efficiency of exit versus entry screening of travellers at commercial airports. Methods We analysed International Air Transport Association data for worldwide flight schedules between Sept 1, 2014, and Dec 31, 2014, and historic traveller flight itinerary data from 2013 to describe expected global population movements via commercial air travel out of Guinea, Liberia, and Sierra Leone. Coupled with Ebola virus surveillance data, we modelled the expected number of internationally exported Ebola virus infections, the potential effect of air travel restrictions, and the efficiency of airport-based traveller screening at international ports of entry and exit. We deemed individuals initiating travel from any domestic or international airport within these three countries to have possible exposure to Ebola virus. We deemed all other travellers to have no significant risk of exposure to Ebola virus. Findings Based on epidemic conditions and international flight restrictions to and from Guinea, Liberia, and Sierra Leone as of Sept 1, 2014 (reductions in passenger seats by 51% for Liberia, 66% for Guinea, and 85% for Sierra Leone), our model projects 2·8 travellers infected with Ebola virus departing the above three countries via commercial flights, on average, every month. 91 547 (64%) of all air travellers departing Guinea, Liberia, and Sierra Leone had expected destinations in low-income and lower-middle-income countries. Screening international travellers departing three airports would enable health assessments of all travellers at highest risk

  15. Chemical Composition of the Aerosol Fine Fraction during African Dust Events as part of the Dust ATtACk Experiment in the Caribbean Region

    NASA Astrophysics Data System (ADS)

    Vallejo, Pamela; Formenti, Paola; Desboeufs, Karine; Quiñones, Mariana; Chevaillier, Servanne; Santos, Stephanie; Andrews, Elizabeth; Ogren, John A.; Mayol-Bracero, Olga L.

    2015-04-01

    We present results on the assessment of aerosols' chemical composition at the atmospheric observatory of Cabezas de San Juan in Fajardo, Puerto Rico, during the summers of 2011 and 2012, where periods in the presence and absence of dust were studied under the framework of the Dust-ATtACk (Dust- Aging and Transport, from Africa to the Caribbean) experiment. Dust events were identified through observation and using air-mass back-trajectories, Saharan Air Layer images, measurements of aerosol optical thickness (AOT), in situ scattering and absorption coefficients, and chemical analyses. Results obtained for intense dust events were characterized by higher concentration of coarse particles, higher scattering and absorption coefficients (up to 100 Mm-1 and 5 Mm-1 at 550 and 530 nm, respectively), higher AOT (from 0.4 to 0.8) values, and higher concentration of elements associated with mineral dust (e.g., Si μ3 g/m3 compared to background concentrations of 0.15 μg/m3, obtained from XRF analysis). Elemental composition of the fine fraction (Dp < 1.8 μm), analyzed by ICP-OES, also yielded higher average concentrations during dust events of, for example, Fe (0.045 μg m-3, vs 0.016 μg m-3 during low or no dust). Detailed results of the submicron fraction composition for the carbonaceous aerosol (total carbon, organic carbon, black carbon), total nitrogen, the water-soluble organic carbon, water-soluble ions, and the elemental composition with their possible sources will be presented at the meeting.

  16. Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

    USGS Publications Warehouse

    Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

    2011-01-01

    Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

  17. Respirable coal dust exposure and respiratory symptoms in South-African coal miners: A comparison of current and ex-miners

    SciTech Connect

    Naidoo, R.N.; Robins, T.G.; Seixas, N.; Lalloo, U.G.; Becklake, M.

    2006-06-15

    Dose-response associations between respirable dust exposure and respiratory symptoms and between symptoms and spirometry outcomes among currently employed and formerly employed South-African coal miners were investigated. Work histories, interviews, and spirometry and cumulative exposure were assessed among 684 current and 212 ex-miners. Results: Lower prevalences of symptoms were found among employed compared with ex-miners. Associations with increasing exposure for symptoms of phlegm and past history of tuberculosis were observed, whereas other symptom prevalences were higher in the higher exposure categories. Symptomatic ex-miners exhibited lower lung-function compared to the nonsymptomatic. Compared with published data, symptoms rates were low in current miners but high in ex-miners. Although explanations could include the low prevalence of smoking and/or reporting/selection bias, a 'Survivor' and/or a 'hire' effect is more likely, resulting in an underestimation of the dust-related effect.

  18. Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Boucher, H.; Caquineau, S.; Chevaillier, S.; Cuesta, J.; Formenti, P.

    2014-10-01

    Experimental estimations of the infrared refractive index of African mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5-25 μm. Five dust samples collected at Banizoumbou (Niger) and Tamanrasset (Algeria) during dust events originated from different Western Saharan and Sahelian areas have been investigated. The real (n) and imaginary (k) parts of the refractive index obtained for the different dust samples vary in the range 1.1-2.7 and 0.05-1.0, respectively, and are strongly sensitive to the mineralogical composition of the particles, especially in the 8-12 and 17-25 μm spectral intervals. Dust absorption is controlled mainly by clays (kaolinite, illite, smectite) and, to a lesser extent, by quartz and calcium-rich minerals (e.g. calcite, gypsum). Significant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the OPAC (Optical Properties of Aerosols and Clouds) database. The different data sets appear comparable in magnitude, with our values of n and k falling within the range of variability of past studies. However, literature data fail in accurately reproducing the spectral signatures of the main minerals, in particular clays, and they significantly overestimate the contribution of quartz. Furthermore, the real and the imaginary parts of the refractive index from some literature studies are found not to verify the Kramers-Kronig relations, thus being theoretically incorrect. The comparison between our results, from western Africa, and literature data, from different locations in Europe, Africa, and the Caribbean, nonetheless, confirms the expected large variability of the dust infrared refractive index. This highlights the necessity for an extended systematic investigation of dust properties at infrared wavelengths. For the five analysed dust samples, aerosol intensive optical properties relevant to

  19. Mesoscale modeling and satellite observation of transport and mixing of smoke and dust particles over northern sub-Saharan African region

    NASA Astrophysics Data System (ADS)

    Yang, Zhifeng; Wang, Jun; Ichoku, Charles; Hyer, Edward; Zeng, Jing

    2013-11-01

    transport and vertical distribution of smoke and dust aerosols over the northern sub-Saharan African region are simulated in the Weather Research and Forecasting model with Chemistry (WRF-Chem), which uses hourly dynamic smoke emissions from the Fire Locating and Modeling of Burning Emissions database derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) fire products. Model performance for February 2008 is evaluated using MODIS true color images, aerosol optical depth (AOD) measurements from the Aerosol Robotic Network, MODIS AOD retrievals, and the Cloud-Aerosol Lidar data with Orthogonal Polarization (CALIOP) atmospheric backscattering and extinction products. Specification of smoke injection height of 650 m in WRF-Chem yields aerosol vertical profiles that are most consistent with CALIOP observations of aerosol layer height. Between the equator and 10°N, Saharan dust is often mixed with smoke near the surface, and their transport patterns manifest the interplay of trade winds, subtropical highs, precipitation associated with the Intertropical Convergence Zone, and the high mountains located near the Great Rift Valley region. At the 700 hPa level and above, smoke layers spread farther to the north and south and are often above the dust layers over the Sahel region. In some cases, transported smoke can also be mixed with dust over the Saharan region. Statistically, 5% of the CALIOP valid measurements in February 2007-2011 show aerosol layers either above or between the clouds, reinforcing the importance of the aerosol vertical distribution for quantifying aerosol impact on climate in the Sahel region.

  20. Laboratory chamber measurements of the longwave extinction spectra and complex refractive indices of African and Asian mineral dusts

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Formenti, P.; Styler, S. A.; Pangui, E.; Doussin, J.-F.

    2014-09-01

    In this study we present the first results from laboratory chamber experiments newly designed to investigate the longwave optical properties of mineral dust. Extinction spectra in the 2-16 µm range have been measured in situ (T = 293 K, RH < 2%) for polydispersed pure dust aerosols generated from natural parent soils from Tunisia, Niger, and the Gobi desert. Data are used in combination with particle size distributions to estimate the complex refractive index of each dust sample. Our results show that the magnitude and spectral dependence of the dust extinction and refractive indices differ according to particle mineralogy, suggesting the necessity for regionally resolved optical properties for modeling dust radiative effects in the longwave. The magnitude of extinction is controlled by the particle size distribution and remains significant down to low coarse particle concentrations, indicating that the longwave effect of mineral dust persists throughout long-range transport and is thus relevant at the global scale.

  1. Holocene dust records from the West African Sahel and their implications for changes in climate and land surface conditions

    NASA Astrophysics Data System (ADS)

    Cockerton, Helen E.; Holmes, Jonathan A.; Street-Perrott, F. Alayne; Ficken, Katherine J.

    2014-07-01

    We reconstructed aeolian dust accumulation during the Holocene from two radiocarbon-dated lake-sediment sequences from the Manga Grasslands in northeastern Nigeria in order to investigate long-term changes in the Harmattan dust system over West Africa and evaluate their possible causes. Flux values were low in the early Holocene, decreasing further to a minimum at around 6.2 kyr B.P. after which time they increased, steadily until around 2 kyr B.P. and then more sharply after this time. The long-term variations in dust flux agree broadly with changes in the exposed area of the Lake Chad Basin to the northeast of the study sites, which vary inversely with the volume of Paleolake Megachad. More proximal sources of dust, including the fine fraction of local dune sand and floodplains of nearby rivers, have also made a contribution to the total dust load during times of enhanced dune and fluvial activity. Sharp rises in dust flux over the past century may be related to human activity. Broad patterns of change in dust flux during the Holocene agree with other reconstructions over the same period. However, we see no evidence for a stepped rise during the middle Holocene, as seen at some sites from the northeastern tropical Atlantic, suggesting that controls on the Harmattan dust system have differed from those affecting dust deposition elsewhere across northern Africa.

  2. Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Di Biagio, C.; Boucher, H.; Caquineau, S.; Chevaillier, S.; Cuesta, J.; Formenti, P.

    2014-04-01

    Experimental estimations of the infrared refractive index of African mineral dust have been retrieved from laboratory measurements of particle transmission spectra in the wavelength range 2.5-25 μm. Five dust samples collected at Banizoumbou (Niger) and Tamanrasset (Algeria) during dust events originated from different Western Saharan and Sahelian areas have been investigated. The obtained real (n) and imaginary (k) parts of the refractive index for the different dust cases vary in the range 1.1-2.7 and 0.05-1.0, respectively, and appear to be strongly sensitive to the mineralogical composition of the particles, especially in the 8-12 μm and 17-25 μm spectral intervals. Dust absorption is controlled mainly by clays, and, in minor fraction, by quartz and Ca-rich minerals. Size distribution, and the coarse fraction in particular, plays also a role in determining the refractive index. Significant differences are obtained when comparing our results with existing experimental estimations available in the literature, and with the values of the OPAC (Optical Properties of Aerosols and Clouds) database. The different datasets appear comparable in magnitude, with our values of n and k falling in the range of variability of past studies. However, literature data fail in accurately reproducing the spectral signatures of main minerals, in particular clays, and they significantly overestimate the contribution of quartz. We also found that the real and the imaginary parts of the refractive index from part of literature studies do not verify Kramers-Kronig relations, thus resulting theoretically incorrect. The comparison between our results, from Western Africa, and literature data, from different locations in Europe, Africa, and the Caribbean, nonetheless, confirms the expected large variability of the infrared refractive index of dust, thus highlighting the necessity for an extended systematic investigation. Aerosol intensive optical properties relevant to radiative transfer

  3. Influence of the inter tropical discontinuity on Harmattan dust deposition in Ghana

    NASA Astrophysics Data System (ADS)

    Lyngsie, G.; Olsen, J. L.; Awadzi, T. W.; Fensholt, R.; Breuning-Madsen, H.

    2013-09-01

    The Harmattan is a dry dust-laden continental wind, and in the boreal winter Harmattan dust plumes affects many West African countries, including Ghana. When the Harmattan is strongest the southern part of Ghana is affected by the Inter Tropical Discontinuity (ITD). In this study, we investigate if the ITD functions as a barrier, preventing long transported Harmattan dust to settle south of, and below, it. This is done by analyzing a Harmattan dust outbreak, mapped using Earth observation (EO) data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) platform, coupled with data from West African AERONET stations, and comparing these observations with wind data from NOAA's Air Resources Laboratory (ARL) program and the mineral suite of samples from seasonal dust deposits in north and south Ghana. In northern Ghana traces of minerals indicate a weak influence of particles from an arid environment, which is found consistent with the mapped dust plumes and NE wind directions. In southern Ghana the mineral composition show no sediments of an arid origin, the mapped dust plumes is less intense, and the surface wind directions and wind mass trajectories are more varying with lower wind speeds. Based on the results of this study it is concluded that dust deposited, or measured near ground, in the Harmattan period under the ITD, and south of it, does not contain material from the Chad Basin due to the local winds conditions.

  4. Short communication: Strengthening sub-national communicable disease surveillance in a remote Pacific Island country by adapting a successful African outbreak surveillance model.

    PubMed

    Nelesone, Tekaai; Durrheim, David N; Speare, Richard; Kiedrzynski, Tom; Melrose, Wayne D

    2006-01-01

    Successful communicable disease surveillance depends on effective bidirectional information flow between clinicians at the periphery and communicable disease control units at regional, national and global levels. Resource-poor countries often struggle to establish and maintain the crucial link with the periphery. A simple syndrome-based outbreak surveillance system initially developed and evaluated in Mpumalanga Province, South Africa was adapted for the Pacific island nation of Tuvalu. Eight syndromes were identified for surveillance: acute flaccid paralysis (poliomyelitis), profuse watery diarrhoea (cholera), diarrhoea outbreak, dysentery outbreak, febrile disease with abdominal symptoms and headache (typhoid), febrile disease with generalized non-blistering rash (measles), febrile disease with intense headache and/or neck stiffness with or without haemorrhagic rash (meningococcal meningitis), and outbreaks of other febrile diseases of unknown origin. A user-oriented manual, the Tuvalu Outbreak Manual (http://www.wepi.org/books/tom/), was developed to support introduction of the surveillance system. Nurses working in seven outer island clinics and the hospital outpatient department on the main island rapidly report suspected outbreaks and submit weekly zero-reports to the central communicable disease control unit. An evaluation of the system after 12 months indicated that the Outbreak Manual was regarded as very useful by clinic nurses, and there was early evidence of improved surveillance and response to the disease syndromes under surveillance. PMID:16398751

  5. Chemical Speciation of Water Soluble Ions and Metals of Cloud and Rain Water During the Puerto Rico African Dust and Clouds Study (PRADACS) Campaigns

    NASA Astrophysics Data System (ADS)

    Torres, E.; Valle Diaz, C. J.; Lee, T.; Collett, J. L.; Fitzgerald, E.; Cuadra-Rodriguez, L. A.; Prather, K. A.; Sánchez, M.; McDowell, W. H.; Mayol-Bracero, O. L.

    2013-05-01

    The underlying physico-chemical processes of dust particles interactions are poorly understood; even less understood is how aging impacts cloud properties and climate as the particles travel from Africa to the Caribbean region. Caribbean landmasses have tropical montane cloud forests (TMCFs) that are tightly coupled to the atmospheric hydrologic cycle. TMCFs are ecosystems to study the effects African Dust (AD) on cloud formation and precipitation as these are very sensitive ecosystems that respond to small changes in climate. As part of the Puerto Rico African Dust and Clouds Study (PRADACS), chemical analyses were performed on cloud and rain water samples collected at Pico del Este (PE) station in Luquillo, PR (1051 masl) during campaigns held from 2010 to 2012. At PE, two cloud collectors (i.e., single stage (Aluminum version), a 2-stage (Teflon version) Caltech Active Strand Cloudwater Collector (CASCC)), a rainwater collector, and anAerosol Time-Of-Flight Mass Spectrometer (ATOFMS) were operated. Chemical analyses performed on collected samples include pH, conductivity, ion chromatography (IC), and inductive coupled plasma (ICP). Results from these campaigns showed that on days that had air masses with the influence of AD, cloud water samples had higher conductivity and pH values on average (up to 5.7 and 180μS/cm, respectively) than those with air masses without AD influence. An increase in the concentrations of water-soluble ions like non-sea salt calcium and magnesium, and metals like magnesium, calcium and aluminum was observed and the appearance of iron was seen on ICP analyses. The ATOFMS, showed an increase on the amount of particles during AD influence with composition of aluminum, silicates, potassium, iron and titanium aerosols. The increase on the aforementioned species was constant in the three years of sampling, which give us confidence in the identification of the chemical species that are present during the influence of AD.

  6. Sources, Sinks, and Transatlantic Transport of North African Dust Aerosol: A Multimodel Analysis and Comparison With Remote Sensing Data

    NASA Technical Reports Server (NTRS)

    Kim, Dongchul; Chin, Mian; Yu, Hongbin; Diehl, Thomas; Tan, Qian; Kahn, Ralph A.; Tsigaridis, Kostas; Bauer, Susanne E.; Takemura, Toshihiko; Pozzoli, Luca; Bellouin, Nicolas; Schulz, Michael; Peyridieu, Sophie; Chedin, Alain; Koffi, Brigitte

    2014-01-01

    This study evaluates model-simulated dust aerosols over North Africa and the North Atlantic from five global models that participated in the Aerosol Comparison between Observations and Models phase II model experiments. The model results are compared with satellite aerosol optical depth (AOD) data from Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Sea-viewing Wide Field-of-view Sensor, dust optical depth (DOD) derived from MODIS and MISR, AOD and coarse-mode AOD (as a proxy of DOD) from ground-based Aerosol Robotic Network Sun photometer measurements, and dust vertical distributions/centroid height from Cloud Aerosol Lidar with Orthogonal Polarization and Atmospheric Infrared Sounder satellite AOD retrievals. We examine the following quantities of AOD and DOD: (1) the magnitudes over land and over ocean in our study domain, (2) the longitudinal gradient from the dust source region over North Africa to the western North Atlantic, (3) seasonal variations at different locations, and (4) the dust vertical profile shape and the AOD centroid height (altitude above or below which half of the AOD is located). The different satellite data show consistent features in most of these aspects; however, the models display large diversity in all of them, with significant differences among the models and between models and observations. By examining dust emission, removal, and mass extinction efficiency in the five models, we also find remarkable differences among the models that all contribute to the discrepancies of model-simulated dust amount and distribution. This study highlights the challenges in simulating the dust physical and optical processes, even in the best known dust environment, and stresses the need for observable quantities to constrain the model processes.

  7. Intercomparison of Satellite Dust Retrieval Products over the West African Sahara During the Fennec Campaign in June 2011

    NASA Technical Reports Server (NTRS)

    Banks, J.R.; Brindley, H. E.; Flamant, C.; Garay, M. J.; Hsu, N. C.; Kalashnikova, O. V.; Klueser, L.; Sayer, A. M.

    2013-01-01

    Dust retrievals over the Sahara Desert during June 2011 from the IASI, MISR, MODIS, and SEVIRI satellite instruments are compared against each other in order to understand the strengths and weaknesses of each retrieval approach. Particular attention is paid to the effects of meteorological conditions, land surface properties, and the magnitude of the dust loading. The period of study corresponds to the time of the first Fennec intensive measurement campaign, which provides new ground-based and aircraft measurements of the dust characteristics and loading. Validation using ground-based AERONET sunphotometer data indicate that of the satellite instruments, SEVIRI is most able to retrieve dust during optically thick dust events, whereas IASI and MODIS perform better at low dust loadings. This may significantly affect observations of dust emission and the mean dust climatology. MISR and MODIS are least sensitive to variations in meteorological conditions, while SEVIRI tends to overestimate the aerosol optical depth (AOD) under moist conditions (with a bias against AERONET of 0.31), especially at low dust loadings where the AOD<1. Further comparisons are made with airborne LIDAR measurements taken during the Fennec campaign, which provide further evidence for the inferences made from the AERONET comparisons. The effect of surface properties on the retrievals is also investigated. Over elevated surfaces IASI retrieves AODs which are most consistent with AERONET observations, while the AODs retrieved by MODIS tend to be biased low. In contrast, over the least emissive surfaces IASI significantly underestimates the AOD (with a bias of -0.41), while MISR and SEVIRI show closest agreement.

  8. A seven year record of Saharan dust outbreaks over the Central Mediterranean Sea:chemical characterization, size distribution and optical properties

    NASA Astrophysics Data System (ADS)

    Becagli, Silvia; Marconi, Miriam; Sferlazzo, Damiano; Bommarito, Carlo; Calzolai, Giulia; Chiari, Massimo; di Sarra, Alcide; Gomez-Amo, Jose Louis; Lucarelli, Franco; Meloni, Daniela; Pace, Giandomenico; Traversi, Rita; Severi, Mirko; Udisti, Roberto

    2013-04-01

    Saharan dust largely affects air pollution and climate. This study aims at determining the mineral contribution to PM10 in the Central Mediterranean Sea based on 7 years of PM10 chemical composition measurements at the island of Lampedusa (35.5°N, 12.6° E). Total content and soluble fractions of selected elements and metals are used to characterize the dust events. The soluble + insoluble contribution is determined by PIXE, (Particles Induced X-ray Emission), while the composition of the soluble fraction by ICP-AES, (Inductively coupled plasma - atomic emission spectroscopy) after extraction with HNO3 at pH1.5. The solubility of each element and its size distribution are analyzed with the aim of obtaining information on their sources, mixing processes, and availability for the environment. The Saharan dust contribution to the total PM was estimated by considering Al, Si, Ca, non-sea-salt Na, K and Fe oxides. During strong Saharan dust events PM10 is often higher than 50μg m-3, and the dust contribution is about 50%. The crustal aerosol amount and contribution to PM10 shows a very small seasonal dependence; conversely, the dust optical depth displays an evident annual cycle, with a strong summer maximum (monthly average aerosol optical depth at 500 nm as large as 0.28 in June-August). We found that only 49% of the events identified from optical properties over the air column display a high dust content at the ground level, demonstrating that Saharan dust transport frequently occurs above the marine boundary layer, with negligible or small impact on the surface aerosol properties. The average size distribution obtained by Optical Particle Counter during the days with high mineral content comprises three modes, whose median radii are at about 0.29 um, 2.2 um, and 7.2 um, respectively. Solubility of each elements present a large variability in the condition of extraction, but usually in Saharan dust events the solubility is lower than in non-Saharan dust events

  9. Yellow Fever Outbreak, Southern Sudan, 2003

    PubMed Central

    Onyango, Clayton O.; Grobbelaar, Antoinette A.; Gibson, Georgina V.F.; Sang, Rosemary C.; Sow, Abdourahmane; Swanepoel, Robert

    2004-01-01

    In May 2003, an outbreak of fatal hemorrhagic fever, caused by yellow fever virus, occurred in southern Sudan. Phylogenetic analysis showed that the virus belonged to the East African genotype, which supports the contention that yellow fever is endemic in East Africa with the potential to cause large outbreaks in humans. PMID:15498174

  10. Retrieval of optical and physical properties of African dust from multiwavelength Raman lidar measurements during the SHADOW campaign in Senegal

    NASA Astrophysics Data System (ADS)

    Veselovskii, I.; Goloub, P.; Podvin, T.; Bovchaliuk, V.; Derimian, Y.; Augustin, P.; Fourmentin, M.; Tanre, D.; Korenskiy, M.; Whiteman, D. N.; Diallo, A.; Ndiaye, T.; Kolgotin, A.; Dubovik, O.

    2016-06-01

    West Africa and the adjacent oceanic regions are very important locations for studying dust properties and their influence on weather and climate. The SHADOW (study of SaHAran Dust Over West Africa) campaign is performing a multiscale and multilaboratory study of aerosol properties and dynamics using a set of in situ and remote sensing instruments at an observation site located at the IRD (Institute for Research and Development) in Mbour, Senegal (14° N, 17° W). In this paper, we present the results of lidar measurements performed during the first phase of SHADOW (study of SaHAran Dust Over West Africa) which occurred in March-April 2015. The multiwavelength Mie-Raman lidar acquired 3β + 2α + 1δ measurements during this period. This set of measurements has permitted particle-intensive properties, such as extinction and backscattering Ångström exponents (BAE) for 355/532 nm wavelengths' corresponding lidar ratios and depolarization ratio at 532 nm, to be determined. The mean values of dust lidar ratios during the observation period were about 53 sr at both 532 and 355 nm, which agrees with the values observed during the SAMUM-1 and SAMUM-2 campaigns held in Morocco and Cabo Verde in 2006 and 2008. The mean value of the particle depolarization ratio at 532 nm was 30 ± 4.5 %; however, during strong dust episodes this ratio increased to 35 ± 5 %, which is also in agreement with the results of the SAMUM campaigns. The backscattering Ångström exponent during the dust episodes decreased to ˜ -0.7, while the extinction Ångström exponent, though negative, was greater than -0.2. Low values of BAE can likely be explained by an increase in the imaginary part of the dust refractive index at 355 nm compared to 532 nm. The dust extinction and backscattering coefficients at multiple wavelengths were inverted to the particle microphysics using the regularization algorithm and the model of randomly oriented spheroids. The analysis performed has demonstrated that the

  11. Chemical and microbiological characterization of atmospheric particulate matter during an intense African dust event in Southern Spain.

    PubMed

    Sánchez de la Campa, Ana; García-Salamanca, Adela; Solano, Jennifer; de la Rosa, Jesús; Ramos, Juan-Luis

    2013-04-16

    This study presents the results of the physicochemical characterization of particulate matter associated with an important dust event from the Sahara area that occurred in the South of Spain in 2010. The chemical composition of the samples reflected the dominance of the crustal component of sand from the Sahara desert, although the presence of Mo, Ti, and V trace elements indicated that the dust contained industrial material; probably collected in its transport from Africa. Microbial biodiversity associated with the dust was low, but dominated by Firmicutes and Proteobacteria. Some Firmicutes (belonging to the genus Bacillus and Sporosarcina) were cultured on solid and liquid medium, which suggested that the transported microbes were alive or present as spores that germinated under favorable conditions. These cultivable microbes in the form of spores were highly resistant to desiccation, heat, and UV light. PMID:23484487

  12. North African dust and its relation to paleoclimate recorded in a sediment core from Northwest Providence Channel, Bahamas

    SciTech Connect

    Eaton, M.R.; Boardman, M.R.

    1985-01-01

    Studies of the vertical distribution of insoluble residue in an 11.7 meter core recovered from 665m water depth within Northwest Providence Channel, Bahamas demonstrate cyclic fluctuations in the content and mineralogy of the insoluble residue. The insoluble residue consists of chlorite, montmorillonite, illite and kaolinite with alternating layers enriched in chlorite or montmorillonite. These fluctuations in the character of insoluble residue correspond to fluctuations of the record of oxygen isotopes and foraminiferal assemblages (paleoclimate) and of carbonate mineralogy (sea level). During glacial periods, insoluble residue concentration is high, dolomite is present and quartz, plagioclase and chlorite concentrations increase. During interglacial periods, insoluble residue concentration is low, dolomite is absent and quartz, plagioclase and chlorite concentration decreases while montmorillonite concentration increases. The source of the insoluble residue is dust derived from North Africa and transported by the Saharan Air Layer coupled with the Northeast Trades. During glacial periods, the source of the dust is the dolomite-rich southern North Africa region. This shift of the dust source suggests that the trade winds transporting the dust during glacial periods also shifted southward or expanded or both.

  13. 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.

  14. An Automated Method of MFRSR Calibration for Aerosol Optical Depth Analysis with Application to an Asian Dust Outbreak over the United States.

    NASA Astrophysics Data System (ADS)

    Augustine, John A.; Cornwall, Christopher R.; Hodges, Gary B.; Long, Charles N.; Medina, Carlos I.; Deluisi, John J.

    2003-02-01

    Over the past decade, networks of Multifilter Rotating Shadowband Radiometers (MFRSR) and automated sun photometers have been established in the United States to monitor aerosol properties. The MFRSR alternately measures diffuse and global irradiance in six narrow spectral bands and a broadband channel of the solar spectrum, from which the direct normal component for each may be inferred. Its 500-nm channel mimics sun photometer measurements and thus is a source of aerosol optical depth information. Automatic data reduction methods are needed because of the high volume of data produced by the MFRSR. In addition, these instruments are often not calibrated for absolute irradiance and must be periodically calibrated for optical depth analysis using the Langley method. This process involves extrapolation to the signal the MFRSR would measure at the top of the atmosphere (I0). Here, an automated clear-sky identification algorithm is used to screen MFRSR 500-nm measurements for suitable calibration data. The clear-sky MFRSR measurements are subsequently used to construct a set of calibration Langley plots from which a mean I0 is computed. This calibration I0 may be subsequently applied to any MFRSR 500-nm measurement within the calibration period to retrieve aerosol optical depth. This method is tested on a 2-month MFRSR dataset from the Table Mountain NOAA Surface Radiation Budget Network (SURFRAD) station near Boulder, Colorado. The resultant I0 is applied to two Asian dust-related high air pollution episodes that occurred within the calibration period on 13 and 17 April 2001. Computed aerosol optical depths for 17 April range from approximately 0.30 to 0.40, and those for 13 April vary from background levels to >0.30. Errors in these retrievals were estimated to range from ±0.01 to ±0.05, depending on the solar zenith angle. The calculations are compared with independent MFRSR-based aerosol optical depth retrievals at the Pawnee National Grasslands, 85 km to the

  15. Organic Extracts from African Dust Storms Stimulate Oxidative Stress and Induce Inflammatory Responses in human lung cells through Nrf2 but not NF-kB

    PubMed Central

    Rodríguez-Cotto, Rosa I.; Ortiz-Martínez, Mario G.; Jiménez-Vélez, Braulio D.

    2015-01-01

    The health impact of the global African dust event (ADE) phenomenon in the Caribbean has been vaguely investigated. Heavy metals in ADE and Non-ADE extracts were evaluated for the formation of reactive oxygen species (ROS) and antioxidant capacity by cells using, deferoxamine mesylate (DF) and N-acetyl-L-cysteine (NAC). Results show that ADE particulate matter 2.5 (PM2.5) induces ROS and stimulates oxidative stress. Pre-treatment with DF reduces ROS in ADE and Non-ADE extracts and in lung cells demonstrating that heavy metals are of utmost importance. Glutathione-S-transferase and Heme Oxygenase 1 mRNA levels are induced with ADE PM and reduced by DF and NAC. ADE extracts induced Nrf2 activity and IL-8 mRNA levels significantly more than Non-ADE. NF-κB activity was not detected in any sample. Trace elements and organic constituents in ADE PM2.5 enrich the local environment load, inducing ROS formation and activating antioxidant-signaling pathways increasing pro-inflammatory mediator expressions in lung cells. PMID:25769104

  16. An Automated Method of MFRSR Calibration for Aerosol Optical Depth Analysis with Application to an Asian Dust Outbreak Over the United States

    SciTech Connect

    Augustine, J. A.; Cornwall, C. R.; Hodges, G. B.; Long, Charles N.; Medina, C. I.; DeLuisi, J. J.

    2003-02-01

    Modern robotic spectral solar instruments designed for retrievals of aerosol optical depth (AOD), such as the Multi-Filter Rotating Shadowband Radiometer (MFRSR ) (Harrison et al. 1994), usually operate in an unattended mode. Thus their raw data sets sample a wide range of atmospheric conditions, most of which are undesirable for aerosol optical depth analysis. In addition, these instruments are often not calibrated for absolute irradiance, and must be calibrated for AOD analysis from their own operational data. For AOD retrievals, this involves extrapolation to the value that the instrument would measure before the sun's beam enters the earth's atmosphere, i.e., the extraterrestrial, or zero air mass signal (I 0). This value is inferred via the Langley method (Shaw 1983). Recently, a method that utilizes component solar measurements (direct and diffuse) to identify totally clear-sky and non-hazy periods (Long and Ackerman 2000) has been used successfully to screen MFRSR data for spectral solar measurements suitable for calibration Langley plots. This method was tested in a proof-of-concept mode on a two-month period during the Spring of 2001 with data from the Table Mountain SURF RAD station near Boulder, Colo. The resultant calibration is subsequently applied to an Asian dust event that occurred within that period, and verified with independent aerosol optical depth measurements from a nearby MFRSR and an automated sun photometer.

  17. A New Look to Interactions of Saharan Dust with Waves in the Tropical Atlantic Storm Track

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.; Colarco, P. R.

    2015-12-01

    This study addresses mechanisms of the interactions between light-absorbing aerosols and transient atmospheric waves, including their feedback onto the mean-circulation in one of the most meteorologically sensitive areas of the world: the tropical western African/eastern Atlantic Ocean. Evidence of these interactions are presented based on analyses of an ensemble of NASA satellite data sets, including aerosol optical thickness (AOT) observations from the Moderate Resolution Imaging Spectro-radiometer (MODIS) and the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), as well as an atmospheric reanalysis from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and a simulation of The Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. We analyzed the components of the rate of change of eddy kinetic energy (EKE) to explore the possible role of dust aerosol radiative forcing on reinforcing energetic terms associated with the African easterly waves (AEWs) during boreal summer seasons when the activity of AEWs peaks. This study shows that the anomalous perturbations in concentration of dust in the oceanic Saharan Air Layer (OSAL) precede amplified growth and decay of the subsequent waves compared to waves occurring prior to dust outbreaks. The amplified EKE associated with dust outbreaks are followed by seeding of new wave packets through enhanced divergence and convergence of ageostrophic geopotential height fluxes in the tropical Atlantic storm track. Meanwhile, the enhanced forcing of the mean-circulation associated with the increased momentum fluxes of the high frequency eddies at the northern track of AEWs occurs with a time-lag after the peak of dust concentration in the OSAL. We suggest that dust radiative heating in the OSAL may act as an additional energy source to amplify the thermal/mechanical activity of eddies in the northern track of the AEWs.

  18. African Dust Storms Reaching Puerto Rican Coast Stimulate the Secretion of IL-6 and IL-8 and Cause Cytotoxicity to Human Bronchial Epithelial Cells (BEAS-2B)

    PubMed Central

    Rodríguez-Cotto, Rosa I.; Ortiz-Martínez, Mario G.; Rivera- Ramírez, Evasomary; Méndez, Loyda B.; Dávila, Julio C.; Jiménez-Vélez, Braulio D.

    2014-01-01

    African dust storm events (ADE) travel across the Atlantic Ocean (ADEAO) and reach the Puerto Rican coast (ADEPRC), potentially impacting air quality and human health. To what extent seasonal variations in atmospheric particulate matter (PM) size fractions, composition and sources trigger respiratory-adverse effects to Puerto Ricans is still unclear. In the present study, we investigated the pro-inflammatory and cytotoxic effects of PM samples harvested during ADEAO (PM10), ADEPRC (PM2.5 and PM10) and Non-ADE (Preand Post-ADEAO and Non-ADEPRC), using BEAS-2B cells. Endotoxins (ENX) in PM2.5 and PM10 extracts and traces of metals (TMET) in PM2.5 extracts were also examined. IL-6 and IL-8 secretion and cytotoxicity were used as endpoints. ADEAO and ADEPRC extracts were found to be more cytotoxic than Non-ADE and ADEAO were more toxic than ADEPRC extracts. PM10 extracts from ADEAO and Post-ADEAO caused significant secretion of IL-8. IL-6 and IL-8 secretion was higher following treatment with PM10 and PM2.5 ADEPRC than with Non-ADEPRC extracts. ENX levels were found to be higher in PM10 ADEAO than in the rest of the samples tested. TMET levels were higher in PM2.5 ADEPRC than in Non-ADEPRC extracts. Deferoxamine significantly reduced cytotoxicity and IL-6 and IL-8 secretion whereas Polymyxin B did not. TMET in PM2.5 fractions is a major determinant in ADEPRC-induced toxicity and work in conjunction with ENX to cause toxicity to lung cells in vitro. ENX and TMET may be responsible, in part, for triggering PM-respiratory adverse responses in susceptible and predisposed individuals. PMID:25002916

  19. African Dust Storms Reaching Puerto Rican Coast Stimulate the Secretion of IL-6 and IL-8 and Cause Cytotoxicity to Human Bronchial Epithelial Cells (BEAS-2B).

    PubMed

    Rodríguez-Cotto, Rosa I; Ortiz-Martínez, Mario G; Rivera-Ramírez, Evasomary; Méndez, Loyda B; Dávila, Julio C; Jiménez-Vélez, Braulio D

    2013-10-01

    African dust storm events (ADE) travel across the Atlantic Ocean (ADEAO) and reach the Puerto Rican coast (ADEPRC), potentially impacting air quality and human health. To what extent seasonal variations in atmospheric particulate matter (PM) size fractions, composition and sources trigger respiratory-adverse effects to Puerto Ricans is still unclear. In the present study, we investigated the pro-inflammatory and cytotoxic effects of PM samples harvested during ADEAO (PM10), ADEPRC (PM2.5 and PM10) and Non-ADE (Preand Post-ADEAO and Non-ADEPRC), using BEAS-2B cells. Endotoxins (ENX) in PM2.5 and PM10 extracts and traces of metals (TMET) in PM2.5 extracts were also examined. IL-6 and IL-8 secretion and cytotoxicity were used as endpoints. ADEAO and ADEPRC extracts were found to be more cytotoxic than Non-ADE and ADEAO were more toxic than ADEPRC extracts. PM10 extracts from ADEAO and Post-ADEAO caused significant secretion of IL-8. IL-6 and IL-8 secretion was higher following treatment with PM10 and PM2.5 ADEPRC than with Non-ADEPRC extracts. ENX levels were found to be higher in PM10 ADEAO than in the rest of the samples tested. TMET levels were higher in PM2.5 ADEPRC than in Non-ADEPRC extracts. Deferoxamine significantly reduced cytotoxicity and IL-6 and IL-8 secretion whereas Polymyxin B did not. TMET in PM2.5 fractions is a major determinant in ADEPRC-induced toxicity and work in conjunction with ENX to cause toxicity to lung cells in vitro. ENX and TMET may be responsible, in part, for triggering PM-respiratory adverse responses in susceptible and predisposed individuals. PMID:25002916

  20. Pertussis (Whooping Cough) Outbreaks

    MedlinePlus

    ... questions about pertussis outbreaks... Resources and Publications Find articles about pertussis outbreaks and resources for outbreak response... Postexposure Antimicrobial Prophylaxis The primary objective of PEP should be to prevent death ...

  1. Synoptic conditions favouring the occurrence of dust transport from Africa toward Sardinia Island.

    NASA Astrophysics Data System (ADS)

    Canu, Annalisa; Pellizzaro, Grazia; Pintus, Gabriella; Duce, Pierpaolo

    2016-04-01

    Dust events that reach Italy have usually origin in the Sahara and Sahel regions (north-western part of Africa), which represent the dust sources nearest to Italy. In those regions the dust-lifting activity occurs in a remarkable way. Every dust event is different from the others; in fact dust transport and dust concentration in the air can vary remarkably depending on the synoptic situation. In Sardinia, dust events are more frequent in the May-November period, but they can also take place in the December-April period. The main aim of this work was to describe dust outbreaks in Sardinia and to identify the main meteorological scenarios that originate the transport of dust towards the central and western Mediterranean Basin. The evaluation of the geographical dispersion of Saharan dust was performed by using MODIS satellite data and Meteosat imagery combined with SKIRON forecasting model. The origin and the trajectory of the dust carried by winds towards Italy were inferred by the NOAA HYSPLIT model (Hybrid Single Particle Lagrangian Integrated Trajectory Model). In addition, PM10 (particulate matter with a diameter of less than 10 μm) and meteorological data registered by the ARPAS (Regional Environmental Protection Agency of Sardinia) monitoring stations were used to highlight the arrival of African air masses in Sardinia. The study was carried out during the 2014. A total of five events occurred during the year (two in spring and three in autumn) were analyzed. The origin of air masses loaded with dust from North Africa was confirmed by satellite imagery and 3-days air mass backward trajectories calculated by the NOAA HYSPLIT model. The analysis of the PM10 daily pattern registered at northern and southern Sardinia sites showed a rising of values during the dust event. The arrival of air masses from Africa caused the daily mean air temperature to rise whereas relative humidity values decreased. Finally, the results showed that all the event analyzed were

  2. Cholera outbreaks in Africa.

    PubMed

    Mengel, Martin A; Delrieu, Isabelle; Heyerdahl, Leonard; Gessner, Bradford D

    2014-01-01

    During the current seventh cholera pandemic, Africa bore the major brunt of global disease burden. More than 40 years after its resurgence in Africa in 1970, cholera remains a grave public health problem, characterized by large disease burden, frequent outbreaks, persistent endemicity, and high CFRs, particularly in the region of the central African Great Lakes which might act as reservoirs for cholera. There, cases occur year round with a rise in incidence during the rainy season. Elsewhere in sub-Saharan Africa, cholera occurs mostly in outbreaks of varying size with a constant threat of widespread epidemics. Between 1970 and 2011, African countries reported 3,221,050 suspected cholera cases to the World Health Organization, representing 46 % of all cases reported globally. Excluding the Haitian epidemic, sub-Saharan Africa accounted for 86 % of reported cases and 99 % of deaths worldwide in 2011. The number of cholera cases is possibly much higher than what is reported to the WHO due to the variation in modalities, completeness, and case definition of national cholera data. One source on country specific incidence rates for Africa, adjusting for underreporting, estimates 1,341,080 cases and 160,930 deaths (52.6 % of 2,548,227 estimated cases and 79.6 % of 209,216 estimated deaths worldwide). Another estimates 1,411,453 cases and 53,632 deaths per year, respectively (50 % of 2,836,669 estimated cases and 58.6 % of 91,490 estimated deaths worldwide). Within Africa, half of all cases between 1970 and 2011 were notified from only seven countries: Angola, Democratic Republic of the Congo, Mozambique, Nigeria, Somalia, Tanzania, and South Africa. In contrast to a global trend of decreasing case fatality ratios (CFRs), CFRs have remained stable in Africa at approximately 2 %. Early propagation of cholera outbreaks depends largely on the extent of individual bacterial shedding, host and organism characteristics, the likelihood of people coming into contact with

  3. Characterization of Saharan Dust in Marine Aerosol at the Cape Verdean Island São Vicente

    NASA Astrophysics Data System (ADS)

    Khanneh, F. W.; Müller, K.; Gnauk, T.; Herrmann, H.

    2010-12-01

    The chemical composition of marine aerosols at the Cape Verde Atmospheric Observatory has been analyzed. This was performed through six intensive field campaigns and continuous measurements from January 2007 until now. For the collection of samples, a high volume DIGITEL DHA-80 sampler (PM10-inlet) was routinely operated throughout the year in a 72 h- sampling period collecting particles on 150 mm quartz fiber filters. In addition, a five-stage BERNER impactor with a PM10 cutoff (0.05-10 µm size range) was used to collect size-resolved samples. The samples were analyzed for ions, OC/EC and trace metals. Our observations show that air masses from the African continent usually accompany Saharan dust storms and contained significant amounts trace metals and organic carbon. Dust events were observed mostly during the winter months of the year. During the events, the contribution of sea salt to the total PM10 mass was found to be low. The sea salt and Saharan dust in the particle were found in the coarse mode fractions while the organics and non sea salt components were observed mostly in the submicron fraction. Iron and calcium showed good correlation with the total particulate mass especially during dust events. Significant differences were observed in the trace metal composition (especially iron) between days of Saharan dust outbreak (about 4.2 Fe, 3.4 Ca, 0.3 Ti, and 0.1 Mn µg/m3) and days without (less than 1.0 ng/m3), confirming that the Sahara desert is an important source of trace minerals in this region of the tropical Northern Atlantic. Typically, ions contributed about 55 % to the PM10 mass but decreased to a minimum of about 7% during dust episodes. OC and EC were found in very low concentrations except during dust events where the concentration increase by about a factor of five due to the influence of air masses from the African continent.

  4. Social media in Ebola outbreak.

    PubMed

    Hossain, L; Kam, D; Kong, F; Wigand, R T; Bossomaier, T

    2016-07-01

    The West African 2014 Ebola outbreak has highlighted the need for a better information network. Hybrid information networks, an integration of both hierarchical and formalized command control-driven and community-based, or ad hoc emerging networks, could assist in improving public health responses. By filling the missing gaps with social media use, the public health response could be more proactive rather than reactive in responding to such an outbreak of global concern. This article provides a review of the current social media use specifically in this outbreak by systematically collecting data from ProQuest Newsstand, Dow Jones Factiva, Program for Monitoring Emerging Diseases (ProMED) as well as Google Trends. The period studied is from 19 March 2014 (first request for information on ProMED) to 15 October 2014, a total of 31 weeks. The term 'Ebola' was used in the search for media reports. The outcome of the review shows positive results for social media use in effective surveillance response mechanisms - for improving the detection, preparedness and response of the outbreak - as a complement to traditional, filed, work-based surveillance approach. PMID:26939535

  5. 57Fe Mössbauer spectroscopy investigations of iron oxidation states in the Harmattan dust nutrient contribution to West African soils

    NASA Astrophysics Data System (ADS)

    Adetunji, Jacob

    2014-12-01

    A variety of investigations have been carried out on Harmattan dust over many decades demonstrating the continuing importance of the Harmattan dust phenomenon. The investigations have included elemental enrichment factors, mineralogical nutrient input through dust deposition on the soil, meteorological studies, etc. Harmattan dust is important, not only for its impact on radio communication and low visibility in the shipping lanes over the Atlantic, but also on the livelihood and health of people living in countries over which the dust-laden Harmattan wind blows. However, so far, the aspect of nutrient mineral deposition on the soil has not been thoroughly investigated and requires attention, since the majority of people living in West Africa rely heavily on agriculture. It is therefore relevant to know the useful nutrients in the Harmattan dust deposited on soils of the region. This study is therefore aimed at determining the ferric-ferrous ratio of the iron-bearing minerals contained in the Harmattan dust, so their nutritional contribution can be considered. The Mössbauer technique is a powerful tool for studying the ferric-ferrous ratio and has therefore been used, for the first time, to determine the oxidation states of iron in the dust samples. The results of the analysis show that the Harmattan dust is seriously deficient in ferrous iron, which is the more soluble Fe-ion, needed in the soil for healthy crops and plants in general.

  6. Saharan dust, lightning and tropical cyclones in the eastern tropical Atlantic during NAMMA-06

    NASA Astrophysics Data System (ADS)

    Jenkins, Gregory S.; Pratt, Aaron

    2008-06-01

    During the summer of 2006, the downstream component of African Monsoon Multidisciplinary Analyses Campaign (NASA-AMMA (NAMMA)) examined African Easterly Waves (AEWs) emerging from the coast of Africa. Six of these disturbances went on to become named systems in the Tropical Atlantic. Two of the six systems (Tropical storm Debby and Hurricane Helene) developed in the extreme eastern Atlantic and were associated with dust outbreaks, elevated ice contents and frequent lightning. Here we show that in the early tropical cyclo-genesis stages of these systems there were thousands of cloud-to-ground (CG) lightning flashes as measured by a ground-lightning network. TRMM overpasses show high precipitation ice content above the freezing level and high latent heat release. Super-cooled water can be inferred in the lower parts of cloud systems in concert with observed high ice concentrations at high altitudes creating charge separation based on the large numbers of CG flashes.

  7. Dust Episodes in Hong Kong (South China) and their Relationship with the Sharav and Mongolian Cyclones and Jet Streams

    NASA Technical Reports Server (NTRS)

    Lee, Y. C.; Wenig, Mark; Zhang, Zhenxi; Sugimoto, Nobuo; Larko, Dave; Diehl, Thomas

    2012-01-01

    The study presented in this paper analyses two dust episodes in Hong Kong, one occurring in March 2006 and the other on 22 March 2010. The latter is the worst dust episode on Hong Kong record. The focus is on the relationship between the dust episodes and the Sharav/Mongolian cyclones and jet streams. The 16 March 2006 episode is traceable to a continental-scale Saharan dust outbreak of 5-9 March 2006 caused by the cold front of an East Mediterranean Sharav cyclone arriving at north-west Africa on 5 March 2006. The eastward movement of the cyclone along the North African coast is clearly illustrated in the geopotential height contours. Simulations by the chemistry transport model GOCART provide a visible evidence of the transport as well as an estimate of contributions from the Sahara to the aerosol concentration levels in Hong Kong. The transport simulations suggest that the dust is injected to the polar jet north of the Caspian Sea, while it is transported eastward simultaneously by the more southerly subtropical jet. The major source of dust for Hong Kong is usually the Gobi desert. Despite the effect of remote sources, the 16 March 2006 dust episode was still mainly under the influence of the Mongolian cyclone cold fronts. In the recent episode of 22 March 2010, the influence of the Mongolian cyclone predominated as well. It appears that the concurrent influence of the Sharav and Mongolian cyclones on Hong Kong and East Asia is not a common occurrence. Besides transporting dusts from non-East Asian sources to Hong Kong and East Asia, the strong subtropical jet on 21 March 2010 (i.e. 1 day prior to the major dust episode) is believed to have strengthened an easterly monsoon surge to South China causing the transport of voluminous dusts to Taiwan and Hong Kong the following day.

  8. Modeling cholera outbreaks

    PubMed Central

    Longini, Ira M.; Morris, J. Glenn

    2014-01-01

    Mathematical modeling can be a valuable tool for studying infectious disease outbreak dynamics and simulating the effects of possible interventions. Here, we describe approaches to modeling cholera outbreaks and how models have been applied to explore intervention strategies, particularly in Haiti. Mathematical models can play an important role in formulating and evaluating complex cholera outbreak response options. Major challenges to cholera modeling are insufficient data for calibrating models and the need to tailor models for different outbreak scenarios. PMID:23412687

  9. Earlier vegetation green-up has reduced spring dust storms.

    PubMed

    Fan, Bihang; Guo, Li; Li, Ning; Chen, Jin; Lin, Henry; Zhang, Xiaoyang; Shen, Miaogen; Rao, Yuhan; Wang, Cong; Ma, Lei

    2014-01-01

    The observed decline of spring dust storms in Northeast Asia since the 1950s has been attributed to surface wind stilling. However, spring vegetation growth could also restrain dust storms through accumulating aboveground biomass and increasing surface roughness. To investigate the impacts of vegetation spring growth on dust storms, we examine the relationships between recorded spring dust storm outbreaks and satellite-derived vegetation green-up date in Inner Mongolia, Northern China from 1982 to 2008. We find a significant dampening effect of advanced vegetation growth on spring dust storms (r = 0.49, p = 0.01), with a one-day earlier green-up date corresponding to a decrease in annual spring dust storm outbreaks by 3%. Moreover, the higher correlation (r = 0.55, p < 0.01) between green-up date and dust storm outbreak ratio (the ratio of dust storm outbreaks to times of strong wind events) indicates that such effect is independent of changes in surface wind. Spatially, a negative correlation is detected between areas with advanced green-up dates and regional annual spring dust storms (r = -0.49, p = 0.01). This new insight is valuable for understanding dust storms dynamics under the changing climate. Our findings suggest that dust storms in Inner Mongolia will be further mitigated by the projected earlier vegetation green-up in the warming world. PMID:25343265

  10. 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 (

  11. Dengue disease outbreak detection.

    PubMed

    Dayama, Pankaj; Sampath, Kameshwaran

    2014-01-01

    Early detection of outbreak of a disease may help in timely and effective public health interventions. Our motivation for this work is to assist EHD planning officer to analyze the incidence data and based on it declare whether there is an outbreak or not. In this paper, we develop ensemble of multiple techniques for detecting dengue disease outbreak. These techniques are applied to dengue incidence data from Singapore and results are summarized. PMID:25160360

  12. Investigation of outbreaks: epidemiology.

    PubMed

    Joseph, Carol

    2013-01-01

    Outbreaks of Legionnaires' disease create high levels of public anxiety and media interest and inevitably consume a great deal of public health resources. Investigations should begin as early as possible in order to rapidly identify suspected sources of infection, control the outbreak and prevent further cases occurring. The investigations should be coordinated by an outbreak control team who work collaboratively within local/national/international public health guidelines and with clear terms of reference. The actions carried out by epidemiologists when investigating community-, hospital-, or travel-associated outbreaks are comprehensively outlined in this chapter. The microbiological and environmental actions that complement this work are discussed in the accompanying chapters. PMID:23150390

  13. 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.

  14. Outbreak of Chikungunya Virus Infection, Vanimo, Papua New Guinea

    PubMed Central

    Reimer, Lisa J.; Dagina, Rosheila; Susapu, Melinda; Bande, Grace; Katusele, Michelle; Koimbu, Gussy; Jimmy, Stella; Ropa, Berry; Siba, Peter M.; Pavlin, Boris I.

    2013-01-01

    In June 2012, health authorities in Papua New Guinea detected an increase in febrile illnesses in Vanimo. Chikungunya virus of the Eastern/Central/Southern African genotype harboring the E1:A226V mutation was identified. This ongoing outbreak has spread to ≥8 other provinces and has had a harmful effect on public health. PMID:23965757

  15. 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.

  16. 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 ...

  17. 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 ...

  18. Geochemical evidence for African dust and volcanic ash inputs to terra rossa soils on carbonate reef terraces, northern Jamaica, West Indies

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2009-01-01

    The origin of red or reddish-brown, clay-rich, "terra rossa" soils on limestone has been debated for decades. A traditional qualitative explanation for their formation has been the accumulation of insoluble residues as the limestone is progressively dissolved over time. However, this mode of formation often requires unrealistic or impossible amounts of carbonate dissolution. Therefore, where this mechanism is not viable and where local fluvial or colluvial inputs can be ruled out, an external source or sources must be involved in soil formation. On the north coast of the Caribbean island of Jamaica, we studied a sequence of terra rossa soils developed on emergent limestones thought to be of Quaternary age. The soils become progressively thicker, redder, more Fe- and Al-rich and Si-poor with elevation. Furthermore, although kaolinite is found in all the soils, the highest and oldest soils also contain boehmite. Major and trace element geochemistry shows that the host limestones and local igneous rocks are not likely source materials for the soils. Other trace elements, including the rare earth elements (REE), show that tephra from Central American volcanoes is not a likely source either. However, trace element geochemistry shows that airborne dust from Africa plus tephra from the Lesser Antilles island arc are possible source materials for the clay-rich soils. A third, as yet unidentified, source may also contribute to the soils. We hypothesize that older, more chemically mature Jamaican bauxites may have had a similar origin. The results add to the growing body of evidence of the importance of multiple parent materials, including far-traveled dust, to soil genesis.

  19. [Nosocomial scabies outbreak].

    PubMed

    Robles García, M; de la Lama López-Areal, J; Avellaneda Martínez, C; Giménez García, R; Cortejoso Gonzalo, B; Vaquero Puerta, J L

    2000-10-01

    A scabies outbreak is reported which appeared in the Inpatient Pneumology Department in a 500-bed hospital. The outbreak began after the admission of a 90-year old woman referred from a nursing home. A total of 27 secondary cases occurred among health care personnel (14) and patients (13); other 7 cases of likely scabies occurred among 198 contacts. Patients were treated with 5% permetrine cream, in three applications one week apart from each other. It was also applied as prophylaxis in non involved patients in a single application. A discussion follows on the medical and preventive recommendations to control the spreading of these outbreak. PMID:11153236

  20. 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.

  1. Low Arabian dust extinction-to-backscatter ratio

    NASA Astrophysics Data System (ADS)

    Mamouri, R. E.; Ansmann, A.; Nisantzi, A.; Kokkalis, P.; Schwarz, A.; Hadjimitsis, D.

    2013-09-01

    Compared to typical values of 50-60 sr of the extinction-to-backscatter ratio (lidar ratio) at 532 nm of western Saharan mineral dust, low dust lidar ratios from 33.7±6.7 to 39.1±5.1 sr were derived from polarization lidar observations at Limassol, Cyprus (34°N, 33°E) during an outbreak of Arabian dust mainly from Syria in September 2011, indicated by particle linear depolarization ratios up to 28%-35%. The applied new polarization-lidar/photometer method for the extraction of the dust-related lidar-ratio information from the lidar data is outlined, and the results of the dust outbreak which lasted over several days are discussed. The results confirm an Aerosol Robotic Network photometer study on Arabian dust lidar ratios.

  2. Mumps Cases and Outbreaks

    MedlinePlus

    ... or cigarettes, might increase spread of the virus. MMR vaccine prevents most, but not all, cases of mumps ... is 78% (range: 49% to 92%) effective. The MMR vaccine protects against currently circulating mumps strains. Outbreaks can ...

  3. Outbreaks and Investigations

    MedlinePlus

    ... Rhizopus Investigation web page. Histoplasmosis in an Illinois Prison Histoplasmosis outbreak at a state prison in Illinois, ... Department of Corrections Coccidioidomycosis (Valley fever) in California Prisons High rates of coccidioidomycosis (Valley fever) at two ...

  4. 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

  5. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, Dániel; Lauretta, Dante S.

    2010-01-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  6. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, D.´niel; Lauretta, Dante S.

    2014-02-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  7. Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8-13 μm) and visible aerosol optical thickness measurements: 1. Measurement procedures and results

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.; Ricchiazzi, P.

    2009-06-01

    The infrared (IR) aerosol optical thickness (AOT) spectra of Saharan dust measured during the Portable Infrared Aerosol Transmission Experiment (PIRATE) are reported. Saharan dust optical thickness (extinction) spectra from 8 to 13 μm were obtained using column-integrated solar transmission measurements in Puerto Rico in July 2005 and Senegal in January and March 2006 (during a dust plume) using a Fourier transform infrared (FTIR) spectrometer. The FTIR measured the solar spectral irradiance in the IR in the presence of Saharan dust, and the AOT was determined by comparing the measured spectra to modeled downwelling spectra without dust for the same atmospheric temperature profile, solar zenith angle, water vapor, and ozone concentrations. The modeled dust-free spectra are generated using the Santa Barbara Disort Atmospheric Radiative Transfer (SBDART) program. The measured dust AOT is compared with modeled AOT spectra obtained using Mie theory with dust indices of refraction from Volz and Fouquart with assumed lognormal size distributions. When the visible AOT values from nearby Aerosol Robotic Network (AERONET) sensors are compared to the IR AOT values, results from various dust loadings show that the IR dust AOT at 9.5 μm is typically only one third that of the visible (670 nm) dust AOT, but there is some evidence that this ratio could increase for larger dust size distributions. The surface IR dust forcing is determined to be about -0.4 W/m2 by summing the dusty and clear irradiance differences.

  8. 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

  9. A coccidioidomycosis outbreak following the Northridge, Calif, earthquake

    USGS Publications Warehouse

    Schneider, E.; Hajjeh, R.A.; Spiegel, R.A.; Jibson, R.W.; Harp, E.L.; Marshall, G.A.; Gunn, R.A.; McNeil, M.M.; Pinner, R.W.; Baron, R.C.; Burger, R.C.; Hutwagner, L.C.; Crump, C.; Kaufman, L.; Reef, S.E.; Feldman, G.M.; Pappagianis, D.; Werner, S.B.

    1997-01-01

    Objective. - To describe a coccidioidomycosis outbreak in Ventura County following the January 1994 earthquake, centered in Northridge, Calif, and to identify factors that increased the risk for acquiring acute coccidioidomycosis infection. Design. - Epidemic investigation, population- based skin test survey, and case-control study. Setting. - Ventura County, California. Results. - In Ventura County, between January 24 and March 15, 1994, 203 outbreak-associated coccidioidomycosis cases, including 3 fatalities, were identified (attack rate [AR], 30 cases per 100 000 population). The majority of cases (56%) and the highest AR (114 per 100 000 population) occurred in the town of Simi Valley, a community located at the base of a mountain range that experienced numerous landslides associated with the earthquake. Disease onset for cases peaked 2 weeks after the earthquake. The AR was 2.8 times greater for persons 40 years of age and older than for younger persons (relative risk, 2.8; 95% confidence interval [CI], 2.1-3.7; P<.001). Environmental data indicated that large dust clouds, generated by landslides following the earthquake and strong aftershocks in the Santa Susana Mountains north of Simi Valley, were dispersed into nearby valleys by northeast winds. Simi Valley case-control study data indicated that physically being in a dust cloud (odds ratio, 3.0; 95% CI, 1.6-5.4; P<.001) and time spent in a dust cloud (P<.001) significantly increased the risk for being diagnosed with acute coccidioidomycosis. Conclusions. - Both the location and timing of cases strongly suggest that the coccidioidomycosis outbreak in Ventura County was caused when arthrospores were spread in dust clouds generated by the earthquake. This is the first report of a coccidioidomycosis outbreak following an earthquake. Public and physician awareness, especially in endemic areas following similar dust cloud- generating events, may result in prevention and early recognition of acute

  10. 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

    June and PM10 in August) and another in March (0.02 for AOD and 2.2 µg m-3 for PM10) - both displaying a similar evolution with exceptions in July and September. The seasonal cycle of the DD contribution to AOD does not follow the pattern of the total AOD (close to a bell shape), whereas both PM10 cycles (total and DD contribution) are more similar to each other in shape, with an exception in September. The interannual evolution of the DD contribution to AOD and PM10 has evidenced a progressive decrease. This decline in the levels of mineral dust aerosols can explain up to 30 % of the total aerosol load decrease observed in the study area during the period 2003-2014. The relationship between columnar and surface DD contribution shows a correlation coefficient of 0.81 for the interannual averages. Finally, synoptic conditions during DD events are also analysed, observing that the north African thermal low causes most of the events ( ˜ 53 %). The results presented in this study highlight the relevance of the area studied since it can be considered representative of the clean background in the western Mediterranean Basin where DD events have a high impact on aerosol load levels.

  11. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    ... contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom panels). These data products from ... as yellowish ripples that obscure a large part of southern Iraq. The dust is easy to discern over the dark waters of the teardrop-shaped ...

  12. Andromeda's dust

    SciTech Connect

    Draine, B. T.; Aniano, G.; Krause, Oliver; Groves, Brent; Sandstrom, Karin; Klaas, Ulrich; Linz, Hendrik; Rix, Hans-Walter; Schinnerer, Eva; Schmiedeke, Anika; Walter, Fabian; Braun, Robert; Leroy, Adam E-mail: ganiano@ias.u-psud.fr

    2014-01-10

    Spitzer Space Telescope and Herschel Space Observatory imaging of M31 is used, with a physical dust model, to construct maps of dust surface density, dust-to-gas ratio, starlight heating intensity, and polycyclic aromatic hydrocarbon (PAH) abundance, out to R ≈ 25 kpc. The global dust mass is M {sub d} = 5.4 × 10{sup 7} M {sub ☉}, the global dust/H mass ratio is M {sub d}/M {sub H} = 0.0081, and the global PAH abundance is (q {sub PAH}) = 0.039. The dust surface density has an inner ring at R = 5.6 kpc, a maximum at R = 11.2 kpc, and an outer ring at R ≈ 15.1 kpc. The dust/gas ratio varies from M {sub d}/M {sub H} ≈ 0.026 at the center to ∼0.0027 at R ≈ 25 kpc. From the dust/gas ratio, we estimate the interstellar medium metallicity to vary by a factor ∼10, from Z/Z {sub ☉} ≈ 3 at R = 0 to ∼0.3 at R = 25 kpc. The dust heating rate parameter (U) peaks at the center, with (U) ≈ 35, declining to (U) ≈ 0.25 at R = 20 kpc. Within the central kiloparsec, the starlight heating intensity inferred from the dust modeling is close to what is estimated from the stars in the bulge. The PAH abundance reaches a peak q {sub PAH} ≈ 0.045 at R ≈ 11.2 kpc. When allowance is made for the different spectrum of the bulge stars, q {sub PAH} for the dust in the central kiloparsec is similar to the overall value of q {sub PAH} in the disk. The silicate-graphite-PAH dust model used here is generally able to reproduce the observed dust spectral energy distribution across M31, but overpredicts 500 μm emission at R ≈ 2-6 kpc, suggesting that at R = 2-6 kpc, the dust opacity varies more steeply with frequency (with β ≈ 2.3 between 200 and 600 μm) than in the model.

  13. Planning for smallpox outbreaks

    NASA Astrophysics Data System (ADS)

    Ferguson, Neil M.; Keeling, Matt J.; John Edmunds, W.; Gani, Raymond; Grenfell, Bryan T.; Anderson, Roy M.; Leach, Steve

    2003-10-01

    Mathematical models of viral transmission and control are important tools for assessing the threat posed by deliberate release of the smallpox virus and the best means of containing an outbreak. Models must balance biological realism against limitations of knowledge, and uncertainties need to be accurately communicated to policy-makers. Smallpox poses the particular challenge that key biological, social and spatial factors affecting disease spread in contemporary populations must be elucidated largely from historical studies undertaken before disease eradication in 1979. We review the use of models in smallpox planning within the broader epidemiological context set by recent outbreaks of both novel and re-emerging pathogens.

  14. Measles (Rubeola) Cases and Outbreaks

    MedlinePlus

    ... that caused the large measles outbreak in the Philippines in 2014. 2014: The U.S. experienced 23 measles ... were associated with cases brought in from the Philippines, which experienced a large measles outbreak. For more ...

  15. 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.

  16. 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

  17. Climate Response to Soil Dust Aerosols.

    NASA Astrophysics Data System (ADS)

    Miller, R. L.; Tegen, I.

    1998-12-01

    temperature forced by dust depends upon the extent of overlap between the dust layer and regions of deep convection, in addition to the magnitude of the radiative forcing.Surface temperature is also reduced outside of the dust cloud, which is unlikely to result solely from natural variability of the AGCM.It is suggested that the perturbation by dust to Indian and African monsoon rainfall may depend upon the extent to which ocean dynamical heat transports are altered by dust.

  18. Outbreaks in Health Care Settings.

    PubMed

    Sood, Geeta; Perl, Trish M

    2016-09-01

    Outbreaks and pseudo-outbreaks in health care settings can be complex and should be evaluated systematically using epidemiologic tools. Laboratory testing is an important part of an outbreak evaluation. Health care personnel, equipment, supplies, water, ventilation systems, and the hospital environment have been associated with health care outbreaks. Settings including the neonatal intensive care unit, endoscopy, oncology, and transplant units are areas that have specific issues which impact the approach to outbreak investigation and control. Certain organisms have a predilection for health care settings because of the illnesses of patients, the procedures performed, and the care provided. PMID:27515142

  19. Impact of Interactive Aerosol on the African Easterly Jet in the NASA GEOS-5 Global Forecasting System

    NASA Technical Reports Server (NTRS)

    Reale, O.; Lau, K. M.; da Silva, A.

    2010-01-01

    The real-time treatment of interactive realistically varying aerosol in a global operational forecasting system, as opposed to prescribed (fixed or climatologically varying) aerosols, is a very difficult challenge that only recently begins to be addressed. Experiment results from a recent version of the NASA GEOS-5 forecasting system, inclusive of interactive aerosol treatment, are presented in this work. Four sets of 30 5-day forecasts are initialized from a high quality set of analyses previously produced and documented to cover the period from 15 August to 16 September 2006, which corresponds to the NASA African Monsoon Multidisciplinary Analysis (NAMMA) observing campaign. The four forecast sets are at two different horizontal resolutions and with and without interactive aerosol treatment. The net impact of aerosol, at times in which there is a strong dust outbreak, is a temperature increase at the dust level and decrease in the near-surface levels, in complete agreement with previous observational and modeling studies. Moreover, forecasts in which interactive aerosols are included depict an African Easterly (AEJ) at slightly higher elevation, and slightly displace northward, with respect to the forecasts in which aerosols are not include. The shift in the AEJ position goes in the direction of observations and agrees with previous results.

  20. 2-DUST: Dust radiative transfer code

    NASA Astrophysics Data System (ADS)

    Ueta, Toshiya; Meixner, Margaret

    2016-04-01

    2-DUST is a general-purpose dust radiative transfer code for an axisymmetric system that reveals the global energetics of dust grains in the shell and the 2-D projected morphologies of the shell that are strongly dependent on the mixed effects of the axisymmetric dust distribution and inclination angle. It can be used to model a variety of axisymmetric astronomical dust systems.

  1. Forecasting Infectious Disease Outbreaks

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.

    2015-12-01

    Dynamic models of infectious disease systems abound and are used to study the epidemiological characteristics of disease outbreaks, the ecological mechanisms affecting transmission, and the suitability of various control and intervention strategies. The dynamics of disease transmission are non-linear and consequently difficult to forecast. Here, we describe combined model-inference frameworks developed for the prediction of infectious diseases. We show that accurate and reliable predictions of seasonal influenza outbreaks can be made using a mathematical model representing population-level influenza transmission dynamics that has been recursively optimized using ensemble data assimilation techniques and real-time estimates of influenza incidence. Operational real-time forecasts of influenza and other infectious diseases have been and are currently being generated.

  2. A waterborne tularemia outbreak.

    PubMed

    Greco, D; Allegrini, G; Tizzi, T; Ninu, E; Lamanna, A; Luzi, S

    1987-03-01

    A waterborne tularemia outbreak is described. Forty nine cases were identified in Sansepolcro, a small Medioeval town in the province of Arezzo, Tuscany, Italy. All cases had laterocervical or sub-mandibular adenitis, and occurred within a period of three weeks during March and April 1982. The study showed association between cases and the consumption of water from an unchlorinated water system. Francisella tularensis type 1 was isolated from wild hares captured in the area. PMID:3582597

  3. Mineral dust deposition in Western Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Vincent, Julie; Laurent, Benoit; Bergmatti, Gilles; Losno, Rémi; Bon Nguyen, Elisabeth; Chevaillier, Servanne; Roulet, Pierre; Sauvage, Stéphane; Coddeville, Patrice; Ouboulmane, Noura; Siour, Guillaume; Tovar Sanchez, Antonio; Massanet, Ana; Morales Baquero, Rafael; Di Sarra, Giogio; Sferlazzo, Damiano; Dulac, François; Fornier, Michel; Coursier, Cyril

    2014-05-01

    North African deserts are the world's largest sources of atmospheric mineral dust produced by aeolian erosion. Saharan dust is frequently transported toward Europe over the Mediterranean basin. When deposited in oceanic areas, mineral dust can constitute a key input of nutrients bioavailable for the oceanic biosphere. For instance, Saharan dust deposited in the in the Mediterranean Sea can be a significant source of nutrient like Fe, P and N during summer and autumn. Our objective is to study the deposition Saharan mineral dust in the western Mediterranean basin and to improve how deposition processes are parameterized in 3D regional models. To quantify the deposition flux of Saharan dust in the western Mediterranean region a specific collector (CARAGA) to sample automatically the insoluble atmospheric particle deposition was developed (LISA-ICARE) and a network of CARAGA collectors have been set up. Since 2011, eight CARAGA are then deployed in Frioul, Casset, Montandon and Ersa in France, Mallorca and Granada in Spain, Lampedusa in Italia, and Medenine in Tunisia, along a South-North gradient of almost 2000km from the North African coast to the South of Europe. We observe 10 well identified dust Saharan deposition events at Lampedusa and 6 at Mallorca for a 1-yr sampling period. These dust events are sporadic and the South-North gradient of deposition intensity and frequency is observed (the highest dust mass sampled at the stations are : 2,66 g.m-2 at Lampedusa ; 0,54 g.m-2 at Majorque ; 0,33 g.m-2 at Frioul ; 0,16 g.m-2 at Casset). The ability of the CHIMERE model to reproduce the deposition measurements is tested. The mineral dust plumes simulated over the western Mediterranean basin are also compared to satellite observations (OMI, MODIS) and in-situ measurements performed during the ChArMEx campaign and in the AERONET stations.

  4. Mitigating Infectious Disease Outbreaks

    NASA Astrophysics Data System (ADS)

    Davey, Victoria

    The emergence of new, transmissible infections poses a significant threat to human populations. As the 2009 novel influenza A/H1N1 pandemic and the 2014-2015 Ebola epidemic demonstrate, we have observed the effects of rapid spread of illness in non-immune populations and experienced disturbing uncertainty about future potential for human suffering and societal disruption. Clinical and epidemiologic characteristics of a newly emerged infectious organism are usually gathered in retrospect as the outbreak evolves and affects populations. Knowledge of potential effects of outbreaks and epidemics and most importantly, mitigation at community, regional, national and global levels is needed to inform policy that will prepare and protect people. Study of possible outcomes of evolving epidemics and application of mitigation strategies is not possible in observational or experimental research designs, but computational modeling allows conduct of `virtual' experiments. Results of well-designed computer simulations can aid in the selection and implementation of strategies that limit illness and death, and maintain systems of healthcare and other critical resources that are vital to public protection. Mitigating Infectious Disease Outbreaks.

  5. Allergies, asthma, and dust

    MedlinePlus

    Allergic rhinitis - dust ... make allergies or asthma worse are called triggers. Dust is a common trigger. When your asthma or allergies become worse due to dust, you are said to have a dust allergy. ...

  6. Transpacific transport and evolution of the optical properties of Asian dust

    NASA Astrophysics Data System (ADS)

    Liu, Zhaoyan; Fairlie, T. Duncan; Uno, Itsushi; Huang, Jingfeng; Wu, Dong; Omar, Ali; Kar, Jayanta; Vaughan, Mark; Rogers, Raymond; Winker, David; Trepte, Charles; Hu, Yongxiang; Sun, Wenbo; Lin, Bing; Cheng, Anning

    2013-02-01

    Five years of CALIPSO lidar layer products are used to study transpacific transport of Asian dust. We focus on possible changes to dust intrinsic optical properties during the course of transport, with specific emphasis on changes to particulate depolarization ratio (PDR). PDR distributions for Asian dust transported across the Pacific are compared to previously reported PDR distributions for African dust transported across the Atlantic. African dust shows a slight decreasing trend in PDR during westward transport across the Atlantic during its most active long-range transport season in summer. Asian dust, on the other hand, shows some spatial variability in PDR over the Pacific during its most active long-range transport season in spring. The dust PDR is generally smaller over the ocean than over the Tarim basin and nearby downwind regions. PDR also shows a decreasing trend with latitude moving northward toward the Arctic, together with an increasing trend in the dust aerosol optical depth (AOD) when passing over polluted Asian regions. Possible explanations include (i) the mixing of dust externally or internally with other types of aerosol over the heavily developed industrial regions in East Asia, and (ii) the downstream mixing of dust plumes from different source regions (i.e., Tarim and Gobi). Dust from different source regions exhibits relatively large differences in PDR, with mean values of 0.34±0.07, 0.28±0.06, and 0.30±0.08, respectively, over the Tarim basin, Gobi Desert and Northwest African source regions. Different transport mechanisms are seen for African dust and Asian dust. Asian dust transport is originated by cold fronts and driven by westerly jets. In contrast, summer African transatlantic dust transport is driven by trade winds and is generally well confined in altitude in the free troposphere throughout the tropics and subtropics.

  7. Validation of Saharan Dust Layer Characteristics with Lidar Observations

    NASA Technical Reports Server (NTRS)

    Karyampudi, V. Mohan; Palm, Steve; Reagan, John; Grant, W. B.; Pierce, Harold; Browell, E. V.; Melfi, S. H.

    1998-01-01

    Lidar backscattering profiles available from the LITE data set have been used to estimate the optical depths of the Saharan dust layer over West Africa and E. Atlantic regions, in the context of validating the 3-D conceptual model of the Saharan dust plume proposed by Karyampudi and Carlson. The aerosol extinction profiles and optical depths were retrieved from LITE using the Fernald et al. (1972) method. An extinction-to-backscattering ratio, S(sub a), of 25 was selected for optical depth calculations. The spatial analysis of total column and Saharan dust layer optical depths show higher optical depths over W. Africa that decrease westward over E. Atlantic. The higher optical depths over W. Africa, in general, are associated with heavy dust being raised from the surface in dust source regions. Rapid depletion of these heavy dust particles, perhaps due to sedimentation, appear to decrease the dust loading within the dust layer as the plume leaves the west African continent. Higher optical depths are generally confined to the southern edge of the dust layer, where the middle level jet appears to transport the heavy dust concentrations that tend to mix downward from vertical mixing associated with the strong vertical shears underneath the middle jet. Thus, LITE measurements although, in general, validate the Saharan dust plume conceptual model, show maximum values of optical depths near the southern edge of the dust plume over the E. Atlantic region instead of near the center of the dust plume as described in the conceptual model.

  8. INVESTIGATIONS OF WATERBORNE DISEASE OUTBREAKS

    EPA Science Inventory

    From 1971-2000, there were about 751 waterborne disease outbreaks recognized and reported, with over 500,000 associated cases of illness. From 1989-1994, of 90 total outbreaks, 2% were associated with untreated surface water, 30% with untreated ground water, 42% with treatment de...

  9. Disease Outbreaks Caused by Water.

    ERIC Educational Resources Information Center

    Craun, Gunther F.

    1978-01-01

    Presents a literature review of the disease outbreaks caused by drinking polluted water, covering publications of 1976-77. Some of the waterborn outbreaks included are: (1) cholera; (2) gastroenteritis; (3) giardiasis; and (4) typhoid fever and salmonellosis. A list of 66 references is also presented. (HM)

  10. Chikungunya outbreak in Garo Hills, Meghalaya: An epidemiological perspective

    PubMed Central

    Khan, Siraj Ahmed; Dutta, Prafulla; Topno, Rashmee; Borah, Jani; Chowdhury, Purvita; Mahanta, Jagadish

    2015-01-01

    Background & objectives: Chikungunya (CHIK) fever is a mosquito-borne disease caused by chikungunya virus (CHIKV). Chikungunya infection was first reported from India in 1963 from Kolkata. We report the serological and molecular evidence of an outbreak of chikungunya in northeast India that occurred in Tura, a hilly and forested terrain in Garo Hills district of Meghalaya. Methods: Blood samples (3 ml) collected from hospitalized patients during the outbreak were tested for IgM antibodies against CHIKV and followed up four months later. A repeat survey was carried out in the same area after four months from where cases had been reported. Blood samples were also collected from people with history of fever and body ache in the last four months. Persons showing IgM positivity against CHIKV in the repeat survey were followed up one and a half years later. All samples were also processed by RT-PCR assay for CHIK Envelope (E) 1 gene. Immature mosquitoes were collected, link reared and identified with standard keys. Virus incrimination studies were done on Aedes aegypti and Ae. albopictus mosquitoes collected during the survey. Results: Fever, headache and joint pain were the primary clinical presentations. Twenty three (35.93 %) of 64 samples reported during the outbreak were IgM positive for CHIK. Three samples showed PCR amplification. All these were IgM positive. The sequenced E1 gene revealed that the strains belonged to East Central South African (ECSA) genotype. Interpretation & conclusions: Field survey done after four months revealed that some individuals still had joint pain associated with episodes of headache and fever. It could be inferred that these persons might have contracted infection during the CHIK outbreak four months ago or during the intervening period which caused persistence of sequelae. ECSA genotype was found to be involved in the outbreak. Aedes albopictus was the predominant mosquito species collected during the outbreak. PMID:26139776

  11. Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8-13 μm) and visible aerosol optical thickness measurements: 2. Mineral aerosol mixture analyses

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.

    2009-07-01

    The mineral aerosol mixture composition for the March 2006 Saharan dust storm is assessed in this paper on the basis of the analysis of visible to near-infrared (VIS-NIR) and infrared (IR) aerosol optical thickness (AOT) spectra obtained during the Portable Infrared Aerosol Transmission Experiment (PIRATE). The AOT spectra from 8 to 13 μm were determined using column-integrated solar transmission measurements using a Fourier transform infrared spectrometer. To determine the mineralogy and mixture composition of the dust, we determined the expected mineralogy of dust from the Algerian source region in a dust storm environment. Then we computed the modeled VIS-IR AOT spectra using Mie theory for external and internal mixtures. We compared the modeled VIS-NIR AOT spectra and derived index of refraction and single-scattering albedo with the measured values from AERONET and compared the modeled IR AOT spectra with the values from our IR measurements. The fit between the measured and modeled values was best when we used an extinction resonance correction to the Mie theory results to better account for the exact wavelengths and shapes of some of the AOT peaks for mineral particles. The mineralogy and mixture composition of the best dust model includes external mixtures, internal mixtures, and mineralogy dominated by quartz, illite, and calcite. The modeled mean radius was determined, and several modes were computed in agreement with AERONET results.

  12. Point-source outbreak of coccidioidomycosis in construction workers.

    PubMed

    Cummings, K C; McDowell, A; Wheeler, C; McNary, J; Das, R; Vugia, D J; Mohle-Boetani, J C

    2010-04-01

    Coccidioidomycosis results from inhaling spores of the fungus Coccidioides spp. in soil or airborne dust in endemic areas. We investigated an outbreak of coccidioidomycosis in a 12-person civilian construction crew that excavated soil during an underground pipe installation on Camp Roberts Military Base, California in October 2007. Ten (83.3%) workers developed symptoms of coccidioidomycosis; eight (66.7%) had serologically confirmed disease, seven had abnormal chest radiographs, and one developed disseminated infection; none used respiratory protection. A diagnosis of coccidioidomycosis in an eleventh worker followed his exposure to the outbreak site in 2008. Although episodic clusters of infections have occurred at Camp Roberts, the general area is not associated with the high disease rates found in California's San Joaquin Valley. Measures to minimize exposure to airborne spores during soil-disrupting activities should be taken before work begins in any coccidioides-endemic area, including regions with only historic evidence of disease activity. PMID:19845993

  13. Trial design for evaluating novel treatments during an outbreak of an infectious disease.

    PubMed

    Whitehead, John; Olliaro, Piero; Lang, Trudie; Horby, Peter

    2016-02-01

    Tragically, the outbreak of Ebola that started in West Africa in 2014 has been far more extensive and damaging than any previous outbreaks. The duration of the outbreak has, for the first time, allowed the clinical evaluation of Ebola treatments. This article discusses the designs used for two such clinical trials which have recruited patients in Liberia and Sierra Leone. General principles are outlined for trial designs intended to be deployed quickly, adapt flexibly and provide results soon enough to influence the course of the current epidemic rather than just providing evidence for use should Ebola break out again. Lessons are drawn for the conduct of clinical research in future outbreaks of infectious diseases, where the sequence of events may or may not be similar to the West African Ebola epidemic. PMID:26768556

  14. Performance of distributed bagged stone dust barrier in combating coal-dust explosions

    SciTech Connect

    Plessis, J.J.L. du; Vassard, P.S.

    1999-07-01

    The Kloppersbos Research Facility of the CSIR's Division of Mining Technology has developed a new method of building stone dust barriers. The new barrier makes use of a previous concept of containing stone dust in a bag, but incorporates a new method of rupturing the bag. This was achieved by adapting the closing mechanism and by balancing the stone dust content with the void in the bag. The bagged barrier was extensively tested in the 200-m test gallery. During these tests, it became evident that these bags could be made to rupture and spread stone dust when subjected to smaller forces than those required for the most commonly used passive barrier, the Polish light barrier. To validate this, as well as to gain international acceptance of this new barrier, tests were conducted in the German experimental mine, DMT Tremonia, Dortmund. The barrier was evaluated against numerous methane-initiated coal-dust explosions. The paper describes the successful inhibition of coal-dust explosions at Kloppersbos and DMT tremonia. The barrier has been proven successfully for static pressures of 44 to 82 kpa, dynamic pressures of 12 to 36 kpa and for flame speeds as low as 23 m/s. This barrier is now accepted by the South African government and has been implemented in numerous South African collieries.

  15. Interannual Modulation of Subtropical Atlantic Boreal Summer Dust Variability by ENSO

    SciTech Connect

    DeFlorio, Mike; Goodwin, Ian D.; Cayan, Dan; Miller, Arthur J.; Ghan, Steven J.; Pierce, David; Russell, Lynn M.; Singh, Balwinder

    2016-01-01

    Dust variability in the climate system has been studied for several decades, yet there remains an incomplete understanding of the dynamical mechanisms controlling interannual and decadal variations in dust transport. The sparseness of multi-year observational datasets has limited our understanding of the relationship between climate variations and atmospheric dust. We use available observations and a century-length fully coupled Community Earth System Model (CESM) simulation to show that the El Niño- Southern Oscillation (ENSO) exerts a control on North African dust transport during boreal summer. In CESM, this relationship is stronger over the dusty tropical North Atlantic than near Barbados, one of the few sites having a multi-decadal observed record. During strong La Niña summers in CESM, a statistically significant increase in lower tropospheric easterly wind is associated with an increase in North African dust transport over the Atlantic. Barbados dust and Pacific SST variability are only weakly correlated in both observations and CESM, suggesting that other processes are controlling the crossbasin variability of dust. We also use our CESM simulation to show that the relationship between downstream North African dust transport and ENSO fluctuates on multidecadal timescales and may be modulated by the North Atlantic Oscillation (NAO). Our findings indicate that existing observations of dust over the tropical North Atlantic are not extensive enough to completely describe the variability of dust and dust transport, and demonstrate the importance of global models to supplement and interpret observational records.

  16. Repetitive dengue outbreaks in East Africa: A proposed phased mitigation approach may reduce its impact.

    PubMed

    Baba, Marycelin; Villinger, Jandouwe; Masiga, Daniel K

    2016-05-01

    Dengue outbreaks have persistently occurred in eastern African countries for several decades. We assessed each outbreak to identify risk factors and propose a framework for prevention and impact mitigation. Seven out of ten countries in eastern Africa and three islands in the Indian Ocean have experienced dengue outbreaks between 1823 and 2014. Major risk factors associated with past dengue outbreaks include climate, virus and vector genetics and human practices. Appropriate use of dengue diagnostic tools and their interpretation are necessary for both outbreak investigations and sero-epidemiological studies. Serosurvey findings during inter-epidemic periods have not been adequately utilised to prevent re-occurrence of dengue outbreaks. Local weather variables may be used to predict dengue outbreaks, while entomological surveillance can complement other disease-mitigation efforts during outbreaks and identify risk-prone areas during inter-epidemic periods. The limitations of past dengue outbreak responses and the enormous socio-economic impacts of the disease on human health are highlighted. Its repeated occurrence in East Africa refutes previous observations that susceptibility may depend on race. Alternate hypotheses on heterotypic protection among flaviviruses may not be applied to all ecologies. Prevention and mitigation of severe dengue outbreaks should necessarily consider the diverse factors associated with their occurrence. Implementation of phased dengue mitigation activities can enforce timely and judicious use of scarce resources, promote environmental sanitation, and drive behavioural change, hygienic practices and community-based vector control. Understanding dengue epidemiology and clinical symptoms, as determined by its evolution, are significant to preventing future dengue epidemics. PMID:26922851

  17. Dust agglomeration

    NASA Technical Reports Server (NTRS)

    2000-01-01

    John Marshall, an investigator at Ames Research Center and a principal investigator in the microgravity fluid physics program, is studying the adhesion and cohesion of particles in order to shed light on how granular systems behave. These systems include everything from giant dust clouds that form planets to tiny compressed pellets, such as the ones you swallow as tablets. This knowledge should help us control the grains, dust, and powders that we encounter or use on a daily basis. Marshall investigated electrostatic charge in microgravity on the first and second U.S. Microgravity Laboratory shuttle missions to see how grains aggregate, or stick together. With gravity's effects eliminated on orbit, Marshall found that the grains of sand that behaved ever so freely on Earth now behaved like flour. They would just glom together in clumps and were quite difficult to disperse. That led to an understanding of the prevalence of the electrostatic forces. The granules wanted to aggregate as little chains, like little hairs, and stack end to end. Some of the chains had 20 or 30 grains. This phenomenon indicated that another force, what Marshall believes to be an electrostatic dipole, was at work.(The diagram on the right emphasizes the aggregating particles in the photo on the left, taken during the USML-2 mission in 1995.)

  18. Canyon Dust

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03682 Canyon Dust

    These dust slides are located on the wall of Thithonium Chasma.

    Image information: VIS instrument. Latitude -4.1N, Longitude 275.7E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Dust Slides

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03677 Linear Clouds

    Dust slides are common in the dust covered region called Lycus Sulci. A large fracture is also visible in this image.

    Image information: VIS instrument. Latitude 28.1N, Longitude 226.3E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Dust collector

    SciTech Connect

    Nelson, R.T.

    1986-10-21

    This patent describes a dust collector comprising: (a) a housing having inlet means for receiving air to be cleaned; (b) a plurality of filter units within the housing; (c) a first centrifugal fan arranged for drawing air through the units for removing dust from the air; (d) a plurality of ducts each connected to a corresponding one of the units at one end and to the first fan at the other end to provide passages for air from the units to the first fan, the ducts through a portion of their length being arranged in side-by-side relationship; (e) a second centrifugal fan for providing reverse flow of air through the ducts to the units, the second fan providing a high volume of air at low pressure; (f) a transverse duct connected to the second fan and extending transversely of the portion of the plurality of ducts and adjacent thereto: (g) a plurality of openings providing communication between the transverse duct and each of the plurality of ducts; (i) rotatable means engaging the vanes for sequentially moving the vanes between the first and second positions.

  1. Interstellar Dust: Contributed Papers

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M. (Editor); Allamandola, Louis J. (Editor)

    1989-01-01

    A coherent picture of the dust composition and its physical characteristics in the various phases of the interstellar medium was the central theme. Topics addressed included: dust in diffuse interstellar medium; overidentified infrared emission features; dust in dense clouds; dust in galaxies; optical properties of dust grains; interstellar dust models; interstellar dust and the solar system; dust formation and destruction; UV, visible, and IR observations of interstellar extinction; and quantum-statistical calculations of IR emission from highly vibrationally excited polycyclic aromatic hydrocarbon (PAH) molecules.

  2. Dust Measurements in Tokamaks

    SciTech Connect

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

    2008-04-23

    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 {micro}m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  3. How are climate and marine biological outbreaks functionally linked?

    USGS Publications Warehouse

    Hayes, Marshall L.; Bonaventura, Joseph; Mitchell, Todd P.; Prospero, Joseph M.; Shinn, Eugene A.; Van Dolah, Frances; Barber, Richard T.

    2001-01-01

    Since the mid-1970s, large-scale episodic events such as disease epidemics, mass mortalities, harmful algal blooms and other population explosions have been occurring in marine environments at an historically unprecedented rate. The variety of organisms involved (host, pathogens and other opportunists) and the absolute number of episodes have also increased during this period. Are these changes coincidental? Between 1972 and 1976, a global climate regime shift took place, and it is manifest most clearly by a change in strength of the North Pacific and North Atlantic pressure systems. Consequences of this regime shift are: (1) prolonged drought conditions in the Sahel region of Africa; (2) increased dust supply to the global atmosphere, by a factor of approximately four; (3) increased easterly trade winds across the Atlantic; (4) increased eolian transport of dust to the Atlantic and Caribbean basins; and (5) increased deposition of iron-rich eolian dust to typically iron-poor marine regions. On the basis of well-documented climate and dust observations and the widely accepted increase in marine outbreak rates, this paper proposes that the increased iron supply has altered the micronutrient factors limiting growth of opportunistic organisms and virulence of pathogenic microbes, particularly in macronutrient-rich coastal systems.

  4. Dust feed mechanism

    DOEpatents

    Milliman, Edward M.

    1984-01-01

    The invention is a dust feed device for delivery of a uniform supply of dust for long periods of time to an aerosolizing means for production of a dust suspension. The device utilizes at least two tandem containers having spiral brushes within the containers which transport the dust from a supply to the aerosolizer means.

  5. Electric Dust Devils and Dust Storms

    NASA Astrophysics Data System (ADS)

    Renno, N. O.; Yana, C.

    2004-12-01

    Electrical fields measurements in terrestrial dust devils show that they maintain tremendous charge separation and that their electric fields exceeds the breakdown potential (~10 kV/m) of the Martian atmosphere (Farrell et al., 2002, 2003; Krauss et al., 2002; Renno et al., 2004). Typical Martian dust devils are be up to 100 times larger and much stronger than the small terrestrial analogues. Martian dust devils have higher dust content and may produce even stronger electrical fields. Indeed, the dust devils observed in the Pathfinder images have about 700 times the dust content of the local background atmosphere (Metzger et al., 1999). Thus, strong charge separations and electric-field breakdown are likely to occur on Martian dust devils and dust storms. Our theory (Renno et al., 2004) and laboratory experiments in a Mars chamber shows that collisions between sand and dust particles produce non-thermal microwave radiation. The non-thermal microwave emission allows not only the indirect detection of electric activity but also the determination of the physical properties of Martian sand and dust by remote sensing. Besides being geologically important, electrically charged Martian dust devils and dust storms are potential hazards to Landers and will be dangerous to future astronauts exploring its surface. Indeed, the design of adequate mechanical and electrical systems for these Landers cannot progress effectively without a better understanding of Martian dust devils and dust storms. Moreover, ancillary phenomena associated with electrically charged vortices can ionize atmospheric gases and might have important implications for atmosphere chemistry and even habitability.

  6. Uptake of acid pollutants by mineral dust and their effect on aerosol solubility

    NASA Astrophysics Data System (ADS)

    Saliba, N. A.; Chamseddine, Ashraf

    2012-01-01

    Due to the implications caused by mineral dust and sea-salt heterogeneous reactions with SO 2, NO x and NH 3 derivatives, this study aims to understand the interaction between gaseous and particulate phases; PM10 and PM2.5, in dust-rich and dust-poor environments. During dust outbreaks, the increase in PM10 and PM2.5 mass concentrations by 80 and 75%, respectively, was accompanied with approximately 30% decrease in water soluble inorganic ions. However, nitrate ion concentration, which increased by 36% during dust-rich episodes, was correlated with a 96% increase in gaseous HONO concentration. This implies a significant impact of dust storms on the tropospheric NO 2 to HONO conversion and consequently the formation of nitrate in PMs. Products of the reaction between HONO and mineral dust render atmospheric aerosols more soluble and consequently higher nitrogen deposition fluxes were calculated.

  7. 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.

  8. Early outbreaks of 'epidemic neuromyasthenia'.

    PubMed Central

    Parish, J. G.

    1978-01-01

    The literature of the outbreaks of 'epidemic neuromyasthenia' (ENM) from 1934 to 1955 has been selected to show that the disease affects other people besides young adult females in hospitals and nursing homes. There have been district epidemics, in which the male: female ratio was almost even and several male outbreaks affecting soldiers in barracks. Some outbreaks appear to have been triggered off by an epidemic of poliomyelitis, and the epidemiology of outbreaks in Iceland in 1948 and 1955 suggests that the normal cytopathological effects of poliomyelitis infection have been suppressed by the new disease. In the Durban epidemic (1955) a toxic metabolite was discovered in the urine of many patients and a markedly increased urinary excretion of creatine was noted in two New York State outbreaks. The results of the transmission of an agent from patients with ENM to monkeys suggest that the neurological disorder might be in the form of mild disseminated lesions scattered throughout the nervous system from the brain to peripheral nerves and associated with perivascular round cell infiltration without significant cellular damage. ENM infection was widespread in the North of England in 1955 and associated with lymphocyte abnormalities, which have persisted in some cases for several years. This suggests a continuous organic process. PMID:370810

  9. Physical and optical properties of mineral dust aerosol during the Dust and Biomass-burning Experiment

    NASA Astrophysics Data System (ADS)

    Osborne, S. R.; Johnson, B. T.; Haywood, J. M.; Baran, A. J.; Harrison, M. A. J.; McConnell, C. L.

    2008-12-01

    We present aircraft measurements of dust aerosol during the Dust and Biomass-burning Experiment (DABEX), a project affiliated with the African Monsoon Multidisciplinary Analysis. DABEX took place between 13 January and 3 February 2006 in Sahelian west Africa, with the aircraft based at Niamey, Niger. The data set is augmented with Aerosol Robotic Network (AERONET) data. A mineral dust layer below 1-2 km (sourced from the north) and an overlying biomass burning (BB) layer (sourced from anthropogenic fires to the south) was observed on all days, although variability was observed in both layers. There is evidence of ozone loss within the dust, but with CO levels between 140 and 170 ppbv some history of combustion has occurred. Size distribution of the dust is compared with that of the BB aerosol and with dust measured near Senegal, during the Dust Outflow and Deposition to the Ocean (DODO-1) experiment. For accurate representation of the optical properties, five log-normals to the size distribution across sizes 0.05-5 μm are required, although two log-normals are adequate. The single scattering albedo was almost purely scattering, with values of 0.99 ± 0.01. During the strongest dust events the dust contribution to the column optical depth was 75-80%, compared to a DABEX mean of 50%. The aircraft-derived optical depth varied between 0.19 and 1.07, with the dust-only contribution between 0.07 and 0.81. AERONET optical depth trends are in good agreement with aircraft during DABEX, albeit with a bias to higher aircraft values. Retrieved AERONET aerosol size distributions show variable agreement with the aircraft. Differences between Versions 1 and 2 of the AERONET algorithm are highlighted.

  10. Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Crater wall dust avalanches in southern Arabia Terra.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 10.3, Longitude 24.5 East (335.5 West). 19 meter/pixel resolution.

  11. Mineral dust transport toward Hurricane Helene (2006)

    NASA Astrophysics Data System (ADS)

    Schwendike, Juliane; Jones, Sarah C.; Vogel, Bernhard; Vogel, Heike

    2016-05-01

    This study investigates the transport of mineral dust from its source regions in West Africa toward the developing tropical cyclone Helene (2006) and diagnoses the resulting properties of the air influencing the tropical cyclonegenesis. The model system COSMO-ART (Consortium for Small-Scale Modelling-Aerosols and Reactive Trace gases) in which the emission and transport of mineral dust as well as the radiation feedback are taken into account, was used. The emission of mineral dust between 9 and 14 September 2006 occurred in association with the relatively strong monsoon flow and northeasterly trade winds, with gust fronts of convective systems over land, and with the Atlantic inflow. Additionally, increased surface wind speed was linked to orographical effects at the Algerian Mountains, Atlas Mountains, and the Hoggar. The dust, as part of the Saharan air layer, is transported at low levels by the monsoon flow, the Harmattan, the northeasterly trade winds, and the monsoon trough, and is transported upward in the convergence zone between Harmattan and monsoon flow, in the baroclinic zone along the West African coastline, and by convection. At around 700 hPa the dust is transported by the African easterly jet. Dry and dust-free air is found to the north-northwest of the developing tropical depression due to descent in an anticyclone. Based on the model data, it was possible to distinguish between dry (from the anticyclone), dry and dusty (from the Harmattan and northeasterly trade winds), and dusty and moist air (from the monsoon flow and in the tropical depression due to convection).

  12. Dust particle dynamics in atmospheric dust devils

    NASA Astrophysics Data System (ADS)

    Izvekova, Yulia; Popel, Sergey

    2016-04-01

    Dust particle dynamics is modeled in the Dust Devils (DDs). DD is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall) to large (more than 100 meters wide and more than 1000 meters tall) in Earth's atmosphere. We develop methods for the description of dust particle charging in DDs, discuss the ionization processes in DDs, and model charged dust particle motion. Our conclusions are consistent with the fact that DD can lift a big amount of dust from the surface of a planet into its atmosphere. On the basis of the model we perform calculations and show that DDs are important mechanism for dust uplift in the atmospheres of Earth and Mars. Influence of DD electric field on dynamics of dust particles is investigated. It is shown that influence of the electric field on dust particles trajectories is significant near the ground. At some altitude (more then a quarter of the height of DD) influence of the electric field on dust particles trajectories is negligible. For the calculation of the dynamics of dust electric field can be approximated by effective dipole located at a half of the height of DD. This work was supported by the Russian Federation Presidential Program for State Support of Young Scientists (project no. MK-6935.2015.2).

  13. Ebola virus disease outbreak: what's going on.

    PubMed

    Giraldi, G; Marsella, L T

    2015-01-01

    The current West African Ebola Virus Disease (EVD) outbreak was confirmed in March, 2014, and after months of slow, fragmented responses, the EVD has been recognized as a public health emergency of international concern. The early diagnosis of the disease is difficult without laboratory testing, because its symptoms can be seen in many other infections. In the wake of international agencies advices, the Italian Ministry of Health, on October 1, 2014, released to the Healthcare Professional Workers (HPWs) the Protocol about the management of cases and contacts within the national territory. Due to the increasing number of humanitarian groups and HPWs involved in the field, the probability to have new cases of contamination is higher than ever. Proven specific treatments against EVD are not yet available, however, a variety of compounds have been under testing. The most effective are select monoclonal antibodies that have a high neutralizing potential against epitopes of Ebola Virus. For facing the matter, it is important a comprehensive approach according to the recommendations proposed by the international agencies because no single institution or country has all the capacities to respond to a new and emerging infectious disease. PMID:25748509

  14. An outbreak of lethal adenovirus infection among different otariid species.

    PubMed

    Inoshima, Yasuo; Murakami, Tomoaki; Ishiguro, Naotaka; Hasegawa, Kazuhiro; Kasamatsu, Masahiko

    2013-08-30

    An outbreak of fatal fulminant hepatitis at a Japanese aquarium involved 3 otariids: a California sea lion (Zalophus californianus), a South African fur seal (Arctocephalus pusillus) and a South American sea lion (Otaria flavescens). In a span of about a week in February 2012, 3 otariids showed diarrhea and were acutely low-spirited; subsequently, all three animals died within a period of 3 days. Markedly increased aspartate amino transferase and alanine amino transferase activities were observed. Necrotic hepatitis and eosinophilic intranuclear inclusion bodies in liver hepatocytes and intestinal epithelial cells were observed in the South American sea lion on histological examination. Otarine adenovirus DNA was detected from the livers of all three animals by polymerase chain reaction and determination of the sequences showed that all were identical. These results suggest that a single otarine adenovirus strain may have been the etiological agent of this outbreak of fatal fulminant hepatitis among the different otariid species, and it may be a lethal threat to wild and captive otariids. This is the first evidence of an outbreak of lethal adenovirus infection among different otariid species. PMID:23643878

  15. Observations of Saharan dust in the Caribbean and Implications for Regional Climate Variability

    NASA Technical Reports Server (NTRS)

    Remer, L.; Einaudi, Franco

    2001-01-01

    Massive quantities of dust aerosol, originating at source locations in the Saharan desert are frequently transported westward across the Atlantic. Saharan dust has been frequently identified at ground-based stations in South America, on Barbados, in Florida and in Texas. Recently, in July of 2000, the Puerto Rican Dust Experiment (PRiDE), consisting of researchers from the U.S. Navy, NASA, the University of Miami and the University of Puerto Rico joined together to study this important phenomenon. Numerical forecast models tracked each dust event as the dust left the African continent and transversed the Atlantic. Ground-based, ship-based, airborne and satellite sensors were used to characterize the physical and radiative properties of the dust aerosol. The dust plays an important role in terms of radiative forcing of regional climate. Satellite sensors such as NASA's EOS-MODIS aboard the Terra satellite will provide important continuing information on the dust aerosol and its climatic effects.

  16. Temperature drops and the onset of severe avian influenza A H5N1 virus outbreaks.

    PubMed

    Liu, Chung-Ming; Lin, Shu-Hua; Chen, Ying-Chen; Lin, Katherine Chun-Min; Wu, Tsung-Shu Joseph; King, Chwan-Chuen

    2007-01-01

    Global influenza surveillance is one of the most effective strategies for containing outbreaks and preparing for a possible pandemic influenza. Since the end of 2003, highly pathogenic avian influenza viruses (HPAI) H5N1 have caused many outbreaks in poultries and wild birds from East Asia and have spread to at least 48 countries. For such a fast and wide-spreading virulent pathogen, prediction based on changes of micro- and macro-environment has rarely been evaluated. In this study, we are developing a new climatic approach by investigating the conditions that occurred before the H5N1 avian influenza outbreaks for early predicting future HPAI outbreaks and preventing pandemic disasters. The results show a temperature drop shortly before these outbreaks in birds in each of the Eurasian regions stricken in 2005 and 2006. Dust storms, like those that struck near China's Lake Qinghai around May 4, 2005, exacerbated the spread of this HPAI H5N1 virus, causing the deaths of a record number of wild birds and triggering the subsequent spread of H5N1. Weather monitoring could play an important role in the early warning of outbreaks of this potentially dangerous virus. PMID:17297505

  17. Hazards of explosives dusts

    NASA Astrophysics Data System (ADS)

    The Bureau of Mines has investigated the hazards of military explosives dispersed as dust clouds in a 20-L test chamber. For purposes of personnel safety, the spark ignitability of the explosives in the form of unconfined dust layers was also studied. The 20-L data show that most of the explosive dusts were capable of sustaining explosions as dust clouds dispersed in air and some dusts were even capable of sustaining explosions when dispersed in nitrogen. The finest sizes of explosive dusts were less reactive than the larger sizes; this is opposite to the particle size effect observed previously for the pure fuel dusts. The data for the explosive dusts were compared to those for pure fuel dusts.

  18. Dust Long-Range Transport and the Dust-Radiation Effects on the Modification of the SAL Environment

    NASA Astrophysics Data System (ADS)

    Chen, S.; Wang, S.; Waylonis, M.; Sc

    2010-12-01

    A tracer model based on the Weather Research and Forecast model was developed to simulate dust long-range transport for a dust outbreak event that occurred during July 18-20, 2005. Two numerical experiments were conducted with (ON) and without (OFF) the dust-radiation effects. Simulations were compared with the Aerosol Optical Depth (AOD) from the Moderate Resolution Imaging Spectrometer (MODIS) and results were very reasonable. The influence of dust-radiation effects on the modification of Saharan Air Layer (SAL), which can have a substantial influence on Tropical Cyclone (TC) activities over the eastern Atlantic Ocean, was also investigated. Suspended dust was able to reduce the net downward shortwave radiation by more than 300 W m-2 on the surface. The modification of temperature profiles due to dust-radiation effects resulted in the adjustment of the vertical shear. The dust-radiation effects also modified the dust distribution, which can have a feedback to the heating profile and the vertical shear.

  19. African Aesthetics

    ERIC Educational Resources Information Center

    Abiodun, Rowland

    2001-01-01

    No single traditional discipline can adequately supply answers to the many unresolved questions in African art history. Because of the aesthetic, cultural, historical, and, not infrequently, political biases, already built into the conception and development of Western art history, the discipline of art history as defined and practiced in the West…

  20. Genetic Clues to the 2014 Ebola Outbreak

    MedlinePlus

    ... External link, please review our exit disclaimer . Subscribe Genetic Clues to the 2014 Ebola Outbreak Scientists sequenced ... of Ebola as the outbreak continues. Understanding the genetics of the virus will also help scientists develop ...

  1. Opioids by Injection May Drive HIV Outbreaks

    MedlinePlus

    ... fullstory_159978.html Opioids by Injection May Drive HIV Outbreaks Indiana case offers a lesson for other ... drug abuse epidemic has increased the risk of HIV outbreaks in rural and suburban communities, where up ...

  2. Coping with Stress during Infectious Disease Outbreaks

    MedlinePlus

    · Coping With Stress During Infectious Disease Outbreaks What You Should Know When you hear, read, or watch news about an outbreak ... you may feel anxious and show signs of stress. These signs of stress are normal, and may ...

  3. Saharan dust deposition in the Carpathian Basin and its possible effects on interglacial soil formation

    NASA Astrophysics Data System (ADS)

    Varga, György; Cserháti, Csaba; Kovács, János; Szalai, Zoltán

    2016-09-01

    Several hundred tons of windblown dust material are lifted into the atmosphere and are transported every year from Saharan dust source areas towards Europe having an important climatic and other environmental effect also on distant areas. According to the systematic observations of modern Saharan dust events, it can be stated that dust deflated from North African source areas is a significant constituent of the atmosphere of the Carpathian Basin and Saharan dust deposition events are identifiable several times in a year. Dust episodes are connected to distinct meteorological situations, which are also the determining factors of the different kinds of depositional mechanisms. By using the adjusted values of dust deposition simulations of numerical models, the annual Saharan dust flux can be set into the range of 3.2-5.4 g/m2/y. Based on the results of past mass accumulation rates calculated from stratigraphic and sedimentary data of loess-paleosol sequences, the relative contribution of Saharan dust to interglacial paleosol material was quantified. According to these calculations, North African exotic dust material can represent 20-30% of clay and fine silt-sized soil components of interglacial paleosols in the Carpathian Basin. The syngenetic contribution of external aeolian dust material is capable to modify physicochemical properties of soils and hereby the paleoclimatic interpretation of these pedogene stratigraphic units.

  4. Understanding the Transport of Patagonian Dust and Its Influence on Marine Biological Activity in the South Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Johnson, Matthew; Meskhidze, Nicholas; Kiliyanpilakkil, Praju; Gasso, Santiago

    2010-01-01

    Modeling and remote sensing techniques were applied to examine the horizontal and vertical transport pathways of Patagonian dust and quantify the effect of soluble-iron- laden mineral dust deposition on marine primary productivity in the South Atlantic Ocean (SAO) surface waters. The global chemistry transport model GEOS-Chem, implemented with an iron dissolution scheme, was applied to evaluate the atmospheric transport and deposition of mineral dust and bioavailable iron during two dust outbreaks originating in the source regions of Patagonia. In addition to this "rapidly released" iron, offline calculations were also carried out to estimate the amount of bioavailable iron leached during the residence time of dust in the ocean mixed layer. Model simulations showed that the horizontal and vertical transport pathways of Patagonian dust plumes were largely influenced by the synoptic meteorological patterns of high and low pressure systems. Model-predicted horizontal and vertical transport pathways of Patagonian dust over the SAO were in reasonable agreement with remotely-sensed data. Comparison between remotely-sensed and offline calculated ocean surface chlorophyll-a concentrations indicated that, for the two dust outbreaks examined in this study, the deposition of bioavailable iron in the SAO through atmospheric pathways was insignificant. As the two dust transport episodes examined here represent typical outflows of mineral dust from South American sources, our study suggests that the atmospheric deposition of mineral dust is unlikely to induce large scale marine primary productivity and carbon sequestration in the South Atlantic sector of the Southern Ocean.

  5. IMPROVING WATERBORNE DISEASE OUTBREAK INVESTIGATIONS

    EPA Science Inventory

    This article summarizes the discussions and conclusions of a workshop held December 7-8, 1998, to consider the inherent limitations and weaknesses of waterborne outbreak investigations and make recommendations for their improvement. In recent years, an increased number of suspec...

  6. DISEASE OUTBREAKS CAUSED BY DRINKING WATER

    EPA Science Inventory

    Thirty-two waterborne disease outbreaks were reported to the Centers for Disease Control (CDC) and the Environmental Protection Agency in 1981. The outbreaks occurred in 17 states and involved 4430 cases. This was only 64% of the number of outbreaks that were reported in 1980 and...

  7. The Lake Chad Basin, an Isolated and Persistent Reservoir of Vibrio cholerae O1: A Genomic Insight into the Outbreak in Cameroon, 2010

    PubMed Central

    Kaas, Rolf S.; Ngandjio, Antoinette; Nzouankeu, Ariane; Siriphap, Achiraya; Fonkoua, Marie-Christine; Aarestrup, Frank M.; Hendriksen, Rene S.

    2016-01-01

    The prevalence of reported cholera was relatively low around the Lake Chad basin until 1991. Since then, cholera outbreaks have been reported every couple of years. The objective of this study was to investigate the 2010/2011 Vibrio cholerae outbreak in Cameroon to gain insight into the genomic make-up of the V. cholerae strains responsible for the outbreak. Twenty-four strains were isolated and whole genome sequenced. Known virulence genes, resistance genes and integrating conjugative element (ICE) elements were identified and annotated. A global phylogeny (378 genomes) was inferred using a single nucleotide polymorphism (SNP) analysis. The Cameroon outbreak was found to be clonal and clustered distant from the other African strains. In addition, a subset of the strains contained a deletion that was found in the ICE element causing less resistance. These results suggest that V. cholerae is endemic in the Lake Chad basin and different from other African strains. PMID:27191718

  8. The Lake Chad Basin, an Isolated and Persistent Reservoir of Vibrio cholerae O1: A Genomic Insight into the Outbreak in Cameroon, 2010.

    PubMed

    Kaas, Rolf S; Ngandjio, Antoinette; Nzouankeu, Ariane; Siriphap, Achiraya; Fonkoua, Marie-Christine; Aarestrup, Frank M; Hendriksen, Rene S

    2016-01-01

    The prevalence of reported cholera was relatively low around the Lake Chad basin until 1991. Since then, cholera outbreaks have been reported every couple of years. The objective of this study was to investigate the 2010/2011 Vibrio cholerae outbreak in Cameroon to gain insight into the genomic make-up of the V. cholerae strains responsible for the outbreak. Twenty-four strains were isolated and whole genome sequenced. Known virulence genes, resistance genes and integrating conjugative element (ICE) elements were identified and annotated. A global phylogeny (378 genomes) was inferred using a single nucleotide polymorphism (SNP) analysis. The Cameroon outbreak was found to be clonal and clustered distant from the other African strains. In addition, a subset of the strains contained a deletion that was found in the ICE element causing less resistance. These results suggest that V. cholerae is endemic in the Lake Chad basin and different from other African strains. PMID:27191718

  9. Ebola hemorrhagic fever outbreaks: strategies for effective epidemic management, containment and control.

    PubMed

    Matua, Gerald Amandu; Van der Wal, Dirk Mostert; Locsin, Rozzano C

    2015-01-01

    Ebola hemorrhagic fever, caused by the highly virulent RNA virus of the filoviridae family, has become one of the world's most feared pathogens. The virus induces acute fever and death, often associated with hemorrhagic symptoms in up to 90% of infected patients. The known sub-types of the virus are Zaire, Sudan, Taï Forest, Bundibugyo and Reston Ebola viruses. In the past, outbreaks were limited to the East and Central African tropical belt with the exception of Ebola Reston outbreaks that occurred in animal facilities in the Philippines, USA and Italy. The on-going outbreak in West Africa that is causing numerous deaths and severe socio-economic challenges has resulted in widespread anxiety globally. This panic may be attributed to the intense media interest, the rapid spread of the virus to other countries like United States and Spain, and moreover, to the absence of an approved treatment or vaccine. Informed by this widespread fear and anxiety, we analyzed the commonly used strategies to manage and control Ebola outbreaks and proposed new approaches that could improve epidemic management and control during future outbreaks. We based our recommendations on epidemic management practices employed during recent outbreaks in East, Central and West Africa, and synthesis of peer-reviewed publications as well as published "field" information from individuals and organizations recently involved in the management of Ebola epidemics. The current epidemic management approaches are largely "reactive", with containment efforts aimed at halting spread of existing outbreaks. We recommend that for better outcomes, in addition to "reactive" interventions, "pre-emptive" strategies also need to be instituted. We conclude that emphasizing both "reactive" and "pre-emptive" strategies is more likely to lead to better epidemic preparedness and response at individual, community, institutional, and government levels, resulting in timely containment of future Ebola outbreaks. PMID

  10. Dust Plume off Mauritania

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A thick plume of dust blew off the coast of Mauritania in western Africa on October 2, 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite observed the dust plume as it headed toward the southwest over the Atlantic Ocean. In this image, the dust varies in color from nearly white to medium tan. The dust plume is easier to see over the dark background of the ocean, but the plume stretches across the land surface to the east, as well. The dust plume's structure is clearest along the coastline, where relatively clear air pockets separate distinct puffs of dust. West of that, individual pillows of dust push together to form a more homogeneous plume. Near its southwest tip, the plume takes on yet another shape, with stripes of pale dust fanning out toward the northwest. Occasional tiny white clouds dot the sky overhead, but skies are otherwise clear.

  11. Impact of radiatively interactive dust aerosols in the NASA GEOS-5 climate model: Sensitivity to dust particle shape and refractive index

    NASA Astrophysics Data System (ADS)

    Colarco, Peter R.; Nowottnick, Edward P.; Randles, Cynthia A.; Yi, Bingqi; Yang, Ping; Kim, Kyu-Myong; Smith, Jamison A.; Bardeen, Charles G.

    2014-01-01

    The radiative effects of Saharan dust aerosols are investigated in the NASA GEOS-5 atmospheric general circulation model. A sectional aerosol microphysics model (CARMA) is run online in GEOS-5. CARMA treats the dust aerosol lifecycle, and its tracers are radiatively coupled to GEOS-5. A series of AMIP-style simulations are performed, in which input dust optical properties (particle shape and refractive index) are varied. Simulated dust distributions for summertime Saharan dust compare well to observations, with best results found when the most absorbing dust optical properties are assumed. Dust absorption leads to a strengthening of the summertime Hadley cell circulation, increased dust lofting to higher altitudes, and a strengthening of the African easterly jet, resulting in increased dust atmospheric lifetime and farther northward and westward transport. We find a positive feedback of dust radiative forcing on emissions, in contrast with previous studies, which we attribute to our having a relatively strong longwave forcing caused by our simulating larger effective particle sizes. This longwave forcing reduces the magnitude of midday net surface cooling relative to other studies, and leads to a nighttime warming that results in higher nighttime wind speeds and dust emissions. The radiative effects of dust particle shape have only minor impact on transport and emissions, with small (~5%) impact on top of atmosphere shortwave forcing, in line with previous studies, but relatively more pronounced effects on shortwave atmospheric heating and surface forcing (~20% increase in atmospheric forcing for spheroids). Shape effects on longwave heating terms are of order ~10%.

  12. House-Dust Allergy

    PubMed Central

    Johnson, C. A.

    1982-01-01

    House-dust allergy is a common cause of perennial allergic rhinitis and extrinsic asthma. Symptoms tend to be worse when the patient is in bed. A positive skin test properly performed and interpreted confirms the diagnosis. The house-dust mite is the most important antigenic component of house-dust. Treatment consists of environmental control directed at reducing the mite content of bedroom dust, plus control of symptoms with drugs. Immunotherapy is controversial. ImagesFig. 1 PMID:21286201

  13. China Dust and Sand

    Atmospheric Science Data Center

    2013-04-16

    ... article title:  Dust and Sand Sweep Over Northeast China     View Larger Image ... these views of the dust and sand that swept over northeast China on March 10, 2004. Information on the height of the dust and an ...

  14. Middle East Dust

    Atmospheric Science Data Center

    2013-04-16

    ... only some of the dust over eastern Syria and southeastern Turkey can be discerned. The dust is much more obvious in the center panel, ... 18, 2002 - A large dust plume extends across Syria and Turkey. project:  MISR category:  gallery ...

  15. Dust in the Universe

    ERIC Educational Resources Information Center

    Hemenway, Mary Kay; Armosky, Brad J.

    2004-01-01

    Space is seeming less and less like empty space as new discoveries and reexaminations fill in the gaps. And, ingenuity and technology, like the Spitzer Space Telescope, is allowing examination of the far reaches of the Milky Way and beyond. Even dust is getting its due, but not the dust everyone is familiar with. People seldom consider the dust in…

  16. 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.

  17. 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.

  18. Obesity and African Americans

    MedlinePlus

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  19. Interstellar Dust Instrumentation

    NASA Astrophysics Data System (ADS)

    Sternovsky, Zoltan; Gruen, E.; Horanyi, M.; Drake, K.; Collette, A.; Kempf, S.; Srama, R.; Postberg, F.; Krueger, H.; Auer, S.

    2010-10-01

    Interstellar grains traversing the inner planetary system have been identified by the Ulysses dust detector. Space dust detectors on other missions confirmed this finding. Analysis of the Stardust collectors is under way to search for and analyze such exotic grains. Interstellar dust particles can be detected and analyzed in the near-Earth space environment. New instrumentation has been developed to determine the origin of dust particles and their elemental composition. A Dust Telescope is a combination of a Dust Trajectory Sensor (DTS, Rev. Sci. Instrum. 79, 084501, 2008) together with a high mass resolution mass analyzer for the chemical composition of dust particles in space. Dust particles' trajectories are determined by the measurement of induced electric signals when a charged grain flies through a position sensitive electrode system. A modern DTS can measure dust particles as small as 0.2 micron in radius and dust speeds up to 100 km/s. Large area chemical analyzers of 0.1 m2 sensitive area have been tested at a dust accelerator and it was demonstrated that they have sufficient mass resolution to resolve ions with atomic mass number up to >100 (Earth, Moon and Planets, DOI: 10.1007/s11038-005-9040-z, 2005; Rev. Sci. Instrum. 78, 014501, 2007). The advanced Dust Telescope is capable of identifying interstellar and interplanetary grains, and measuring their mass, velocity vector, charge, elemental and isotopic compositions. An Active Dust Collector combines a DTS with an aerogel or other dust collector materials, e.g. like the ones used on the Stardust mission. The combination of a DTS with a dust collector provides not only individual trajectories of the collected particles but also their impact time and position on the collector which proves essential in finding collected sub-micron sized grains on the collector.

  20. OutbreakTools: A new platform for disease outbreak analysis using the R software

    PubMed Central

    Jombart, Thibaut; Aanensen, David M.; Baguelin, Marc; Birrell, Paul; Cauchemez, Simon; Camacho, Anton; Colijn, Caroline; Collins, Caitlin; Cori, Anne; Didelot, Xavier; Fraser, Christophe; Frost, Simon; Hens, Niel; Hugues, Joseph; Höhle, Michael; Opatowski, Lulla; Rambaut, Andrew; Ratmann, Oliver; Soubeyrand, Samuel; Suchard, Marc A.; Wallinga, Jacco; Ypma, Rolf; Ferguson, Neil

    2014-01-01

    The investigation of infectious disease outbreaks relies on the analysis of increasingly complex and diverse data, which offer new prospects for gaining insights into disease transmission processes and informing public health policies. However, the potential of such data can only be harnessed using a number of different, complementary approaches and tools, and a unified platform for the analysis of disease outbreaks is still lacking. In this paper, we present the new R package OutbreakTools, which aims to provide a basis for outbreak data management and analysis in R. OutbreakTools is developed by a community of epidemiologists, statisticians, modellers and bioinformaticians, and implements classes and methods for storing, handling and visualizing outbreak data. It includes real and simulated outbreak datasets. Together with a number of tools for infectious disease epidemiology recently made available in R, OutbreakTools contributes to the emergence of a new, free and open-source platform for the analysis of disease outbreaks. PMID:24928667

  1. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  2. Geomorphic Aspects of Southern African Dryland Soils

    NASA Astrophysics Data System (ADS)

    Eckardt, Frank

    2015-04-01

    Southern African drylands are host to stable land surfaces with limited denudation rates. The resulting soils manifest long term weathering processes, including leaching, collapse and precipitation of calcium carbonate as is the case in the semi-arid Kalahari. Despite the thickness of some of the Kalahari soils and sands, they are furthermore depicting a range of neotectonic land forms and processes, associated with the contemporary rifting of the southern African continent. This is particularly apparent in satellite imagery and digital elevation data that can be used to examine regional scale surface characteristics. Southern Africa is also home to significant global and regional scale dust sources, which are mostly associated with inland basins and playas. Plumes of dust emitted from playas are able to impact upon downwind soil quality. This can be observed in the both the western Makgadikgadi as well as the Central Namib gravel plain. In the Namib playa dust contributes to the accumulation of gravel plain fines, leaching and massive pedogenic gypsum accumulations. It is apparent that Southern African dryland soils are home to aeolian inputs, host extensive duricrusts and depict neotectonic movement which should be of interest to the wider earth science community.

  3. Communicable Diseases and Outbreak Control.

    PubMed

    Ameli, Jonathan

    2015-10-01

    Infectious disease during an emergency condition can raise the death rate 60 times in comparison to other causes including trauma. An epidemic, or outbreak, can occur when several aspects of the agent (pathogen), population (hosts), and the environment create an ideal situation for spread. Overcrowding, poor regional design and hygiene due to poverty, dirty drinking water, rapid climate changes, and natural disasters, can lead to conditions that allow easier transmission of disease. Once it has been established that an emergency condition exists, there must be a prompt and thorough response for communicable disease control. A camp should be created, and the disease managed rapidly. The overall goals are rapid assessment, prevention, surveillance, outbreak control, and disease management. PMID:27437528

  4. Interannual modulation of subtropical Atlantic boreal summer dust variability by ENSO

    NASA Astrophysics Data System (ADS)

    Deflorio, M. J.; Goodwin, I. D.; Cayan, D. R.; Miller, A. J.; Ghan, S.; Pierce, D. W.; Russell, L. M.; Singh, B.

    2015-12-01

    Dust variability in the climate system has been studied for several decades, yet there remains an incomplete understanding of the dynamical mechanisms controlling interannual and decadal variations in dust transport. The sparseness of multi-year observational datasets has limited our understanding of the relationship between climate variations and atmospheric dust. We use available in situ and satellite observations of dust and a century-length fully coupled Community Earth System Model (CESM) simulation to show that the El Niño-Southern Oscillation (ENSO) exerts a control on North African dust transport during boreal summer. In CESM, this relationship is stronger over the dusty tropical North Atlantic than near Barbados, one of the few sites having a multi-decadal observed record. During strong La Niña summers in CESM, a statistically significant increase in lower tropospheric easterly wind is associated with an increase in North African dust transport over the Atlantic. Barbados dust and Pacific SST variability are only weakly correlated in both observations and CESM, suggesting that other processes are controlling the cross-basin variability of dust. We also use our CESM simulation to show that the relationship between downstream North African dust transport and ENSO fluctuates on multidecadal timescales and is associated with a phase shift in the North Atlantic Oscillation. Our findings indicate that existing observations of dust over the tropical North Atlantic are not extensive enough to completely describe the variability of dust and dust transport, and demonstrate the importance of global models to supplement and interpret observational records.

  5. The transatlantic dust transport from North Africa to the Americas—Its characteristics and source regions

    NASA Astrophysics Data System (ADS)

    Gläser, Gregor; Wernli, Heini; Kerkweg, Astrid; Teubler, Franziska

    2015-11-01

    Transport of Saharan dust over the Atlantic to the Americas is a relevant process since dust is a nutrient for marine and terrestrial ecosystems. It is therefore important to better quantify the frequency and amount of transatlantic dust transport, its preferred altitude and duration, and the regions of dust origin. This study uses a novel combination of Eulerian and Lagrangian diagnostics, applied to a previously validated 5 year simulation of the fifth generation European Centre for Medium Range Weather Forecast-Hamburg-model (ECHAM5)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry model, to quantify these dust transport characteristics and their seasonal variations. Results confirm the previously found preferred transatlantic dust pathways: in boreal winter and spring, African dust is mainly transported below 800 hPa toward South America, whereas in summer and autumn the preferred pathway is to the Caribbean and occurs in a layer up to 500 hPa. The averaged transport duration from dust emission to deposition is 10 days in winter for deposition in the Amazon region and almost 12 days in summer for deposition in the Caribbean. These estimates were obtained by combining correlation analyses of Eulerian dust fluxes and trajectory calculations. The latter were also essential to identify the main source regions of transatlantic dust transport, which were found in all seasons in northwestern Africa (Algeria, Mali, and Mauritania) but not farther east, e.g., in the Bodélé Depression. A specific Lagrangian analysis for this dust emission hot spot suggests that wet deposition associated with the Intertropical Convergence Zone in winter and the African monsoon in summer inhibits Bodélé dust to leave the African continent.

  6. Interstellar Dust - A Review

    NASA Technical Reports Server (NTRS)

    Salama, Farid

    2012-01-01

    The study of the formation and the destruction processes of cosmic dust is essential to understand and to quantify the budget of extraterrestrial organic materials. Although dust with all its components plays an important role in the evolution of interstellar physics and chemistry and in the formation of organic materials, little is known on the formation and destruction processes of carbonaceous dust. Laboratory experiments that are performed under conditions that simulate interstellar and circumstellar environments to provide information on the nature, the size and the structure of interstellar dust particles, the growth and the destruction processes of interstellar dust and the resulting budget of extraterrestrial organic molecules. A review of the properties of dust and of the laboratory experiments that are conducted to study the formation processes of dust grains from molecular precursors will be given.

  7. Light Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    14 October 2004 Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images exhibit wild patterns of dark streaks thought to have formed by the passage of many dust devils. The dust devils disrupt the dust coating the martian surface, leaving behind a streak. However, not all dust devils make streaks, and not all dust devil streaks are dark. Some are light---it simply depends upon which is darker, the substrate or the dust that the spinning vortex disrupts. The example of light-toned dust devil streaks shown here is located in southern Schiaparelli Basin near 5.3oS, 343.3oW. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left/upper left.

  8. Dengue disease outbreak definitions are implicitly variable

    PubMed Central

    Brady, Oliver J.; Smith, David L.; Scott, Thomas W.; Hay, Simon I.

    2015-01-01

    Infectious diseases rarely exhibit simple dynamics. Outbreaks (defined as excess cases beyond response capabilities) have the potential to cause a disproportionately high burden due to overwhelming health care systems. The recommendations of international policy guidelines and research agendas are based on a perceived standardised definition of an outbreak characterised by a prolonged, high-caseload, extra-seasonal surge. In this analysis we apply multiple candidate outbreak definitions to reported dengue case data from Brazil to test this assumption. The methods identify highly heterogeneous outbreak characteristics in terms of frequency, duration and case burden. All definitions identify outbreaks with characteristics that vary over time and space. Further, definitions differ in their timeliness of outbreak onset, and thus may be more or less suitable for early intervention. This raises concerns about the application of current outbreak guidelines for early warning/identification systems. It is clear that quantitatively defining the characteristics of an outbreak is an essential prerequisite for effective reactive response. More work is needed so that definitions of disease outbreaks can take into account the baseline capacities of treatment, surveillance and control. This is essential if outbreak guidelines are to be effective and generalisable across a range of epidemiologically different settings. PMID:25979287

  9. Climate Teleconnections and Recent Patterns of Human and Animal Disease Outbreaks

    NASA Technical Reports Server (NTRS)

    Anyamba, Assaf; Linthicum, Kenneth J.; Small, Jennifer L.; Collins, Katherine M.; Tucker, Compton J.; Pak, Edwin W.; Britch, Seth C.; Eastman, James Ronald; Pinzon, Jorge E.; Russell, Kevin L.

    2011-01-01

    Recent clusters of outbreaks of mosquito-borne diseases (Rift Valley fever and chikungunya) in Africa and parts of the Indian Ocean islands illustrate how interannual climate variability influences the changing risk patterns of disease outbreaks. Extremes in rainfall (drought and flood) during the period 2004 - 2009 have privileged different disease vectors. Chikungunya outbreaks occurred during the severe drought from late 2004 to 2006 over coastal East Africa and the western Indian Ocean islands and in the later years India and Southeast Asia. The chikungunya pandemic was caused by a Central/East African genotype that appears to have been precipitated and then enhanced by global-scale and regional climate conditions in these regions. Outbreaks of Rift Valley fever occurred following excessive rainfall period from late 2006 to late 2007 in East Africa and Sudan, and then in 2008 - 2009 in Southern Africa. The shift in the outbreak patterns of Rift Valley fever from East Africa to Southern Africa followed a transition of the El Nino/Southern Oscillation (ENSO) phenomena from the warm El Nino phase (2006-2007) to the cold La Nina phase (2007-2009) and associated patterns of variability in the greater Indian Ocean basin that result in the displacement of the centres of above normal rainfall from Eastern to Southern Africa. Understanding the background patterns of climate variability both at global and regional scale and their impacts on ecological drivers of vector borne-diseases is critical in long-range planning of appropriate response and mitigation measures.

  10. Measles virus genetic evolution throughout an imported epidemic outbreak in a highly vaccinated population.

    PubMed

    Muñoz-Alía, Miguel Ángel; Fernández-Muñoz, Rafael; Casasnovas, José María; Porras-Mansilla, Rebeca; Serrano-Pardo, Ángela; Pagán, Israel; Ordobás, María; Ramírez, Rosa; Celma, María Luisa

    2015-01-22

    Measles virus circulates endemically in African and Asian large urban populations, causing outbreaks worldwide in populations with up-to-95% immune protection. We studied the natural genetic variability of genotype B3.1 in a population with 95% vaccine coverage throughout an imported six month measles outbreak. From first pass viral isolates of 47 patients we performed direct sequencing of genomic cDNA. Whilst no variation from index case sequence occurred in the Nucleocapsid gene hyper-variable carboxy end, in the Hemagglutinin gene, main target for neutralizing antibodies, we observed gradual nucleotide divergence from index case along the outbreak (0% to 0.380%, average 0.138%) with the emergence of transient and persistent non-synonymous and synonymous mutations. Little or no variation was observed between the index and last outbreak cases in Phosphoprotein, Nucleocapsid, Matrix and Fusion genes. Most of the H non-synonymous mutations were mapped on the protein surface near antigenic and receptors binding sites. We estimated a MV-Hemagglutinin nucleotide substitution rate of 7.28 × 10-6 substitutions/site/day by a Bayesian phylogenetic analysis. The dN/dS analysis did not suggest significant immune or other selective pressures on the H gene during the outbreak. These results emphasize the usefulness of MV-H sequence analysis in measles epidemiological surveillance and elimination programs, and in detection of potentially emergence of measles virus neutralization-resistant mutants. PMID:25445338

  11. Norovirus GII.4 detection in environmental samples from patient rooms during nosocomial outbreaks.

    PubMed

    Nenonen, Nancy P; Hannoun, Charles; Svensson, Lennart; Torén, Kjell; Andersson, Lars-Magnus; Westin, Johan; Bergström, Tomas

    2014-07-01

    Norovirus (NoV) is an important cause of nosocomial gastroenteric outbreaks. This 5-month study was designed to characterize NoV contamination and airborne dispersal in patient rooms during hospital outbreaks. Air vents, overbed tables, washbasins, dust, and virus traps designed to collect charged particles from the air were swabbed to investigate the possibility of NoV contamination in patient rooms during outbreaks in seven wards and in an outbreak-free ward. Symptomatic inpatients were also sampled. Nucleic acid extracts of the samples were examined for NoV RNA using genogroup I (GI) and GII real-time reverse transcription-PCR (RT-PCR). The NoV strains were characterized by RT-PCR, sequencing, and phylogenetic analysis of the RNA-dependent RNA-polymerase-N/S capsid-coding region (1,040 nucleotides [nt]). Patient strains from two outbreaks in one ward were sequenced across the RNA-dependent-RNA-polymerase major capsid-coding region (2.5 kb), including the hypervariable P2 domain. In the outbreak wards, NoV GII was detected in 48 of 101 (47%) environmental swabs and 63 of 108 patients (58%); NoV genotype II.4 was sequenced from 18 environmental samples, dust (n = 8), virus traps (n = 4), surfaces (n = 6), and 56 patients. In contrast, NoV GII was detected in 2 (GII.4) of 28 (7%) environmental samples and in 2 (GII.6 and GII.4) of 17 patients in the outbreak-free ward. Sequence analyses revealed a high degree of similarity (>99.5%, 1,040 nt) between NoV GII.4 environmental and patient strains from a given ward at a given time. The strains clustered on 11 subbranches of the phylogenetic tree, with strong correlations to time and place. The high nucleotide similarity between the NoV GII.4 strains from patients and their hospital room environment provided molecular evidence of GII.4 dispersal in the air and dust; therefore, interventional cleaning studies are justified. PMID:24759712

  12. Norovirus GII.4 Detection in Environmental Samples from Patient Rooms during Nosocomial Outbreaks

    PubMed Central

    Hannoun, Charles; Svensson, Lennart; Torén, Kjell; Andersson, Lars-Magnus; Westin, Johan; Bergström, Tomas

    2014-01-01

    Norovirus (NoV) is an important cause of nosocomial gastroenteric outbreaks. This 5-month study was designed to characterize NoV contamination and airborne dispersal in patient rooms during hospital outbreaks. Air vents, overbed tables, washbasins, dust, and virus traps designed to collect charged particles from the air were swabbed to investigate the possibility of NoV contamination in patient rooms during outbreaks in seven wards and in an outbreak-free ward. Symptomatic inpatients were also sampled. Nucleic acid extracts of the samples were examined for NoV RNA using genogroup I (GI) and GII real-time reverse transcription-PCR (RT-PCR). The NoV strains were characterized by RT-PCR, sequencing, and phylogenetic analysis of the RNA-dependent RNA-polymerase-N/S capsid-coding region (1,040 nucleotides [nt]). Patient strains from two outbreaks in one ward were sequenced across the RNA-dependent-RNA-polymerase major capsid-coding region (2.5 kb), including the hypervariable P2 domain. In the outbreak wards, NoV GII was detected in 48 of 101 (47%) environmental swabs and 63 of 108 patients (58%); NoV genotype II.4 was sequenced from 18 environmental samples, dust (n = 8), virus traps (n = 4), surfaces (n = 6), and 56 patients. In contrast, NoV GII was detected in 2 (GII.4) of 28 (7%) environmental samples and in 2 (GII.6 and GII.4) of 17 patients in the outbreak-free ward. Sequence analyses revealed a high degree of similarity (>99.5%, 1,040 nt) between NoV GII.4 environmental and patient strains from a given ward at a given time. The strains clustered on 11 subbranches of the phylogenetic tree, with strong correlations to time and place. The high nucleotide similarity between the NoV GII.4 strains from patients and their hospital room environment provided molecular evidence of GII.4 dispersal in the air and dust; therefore, interventional cleaning studies are justified. PMID:24759712

  13. Sentinel surveillance system for early outbreak detection in Madagascar

    PubMed Central

    2010-01-01

    Background Following the outbreak of chikungunya in the Indian Ocean, the Ministry of Health directed the necessary development of an early outbreak detection system. A disease surveillance team including the Institut Pasteur in Madagascar (IPM) was organized to establish a sentinel syndromic-based surveillance system. The system, which was set up in March 2007, transmits patient data on a daily basis from the various voluntary general practitioners throughout the six provinces of the country to the IPM. We describe the challenges and steps involved in developing a sentinel surveillance system and the well-timed information it provides for improving public health decision-making. Methods Surveillance was based on data collected from sentinel general practitioners (SGP). The SGPs report the sex, age, visit date and time, and symptoms of each new patient weekly, using forms addressed to the management team. However, the system is original in that SGPs also report data at least once a day, from Monday to Friday (number of fever cases, rapid test confirmed malaria, influenza, arboviral syndromes or diarrhoeal disease), by cellular telephone (encrypted message SMS). Information can also be validated by the management team, by mobile phone. This data transmission costs 120 ariary per day, less than US$1 per month. Results In 2008, the sentinel surveillance system included 13 health centers, and identified 5 outbreaks. Of the 218,849 visits to SGPs, 12.2% were related to fever syndromes. Of these 26,669 fever cases, 12.3% were related to Dengue-like fever, 11.1% to Influenza-like illness and 9.7% to malaria cases confirmed by a specific rapid diagnostic test. Conclusion The sentinel surveillance system represents the first nationwide real-time-like surveillance system ever established in Madagascar. Our findings should encourage other African countries to develop their own syndromic surveillance systems. Prompt detection of an outbreak of infectious disease may lead to

  14. Haul road dust control

    SciTech Connect

    Reed, W.R.; Organiscak, J.A.

    2007-10-15

    A field study was conducted to measure dust from haul trucks at a limestone quarry and a coal preparation plant waste hauling operation. The study found that primarily wind, distance and road treatment conditions notably affected the dust concentrations at locations next to, 50 ft from, and 100 ft away from the unpaved haulage road. Airborne dust measured along the unpaved haul road showed that high concentrations of fugitive dust can be generated with these concentrations rapidly decreasing to nearly background levels within 100 ft of the road. Instantaneous respirable dust measurements illustrated that the trucks generate a real-time dust cloud that has a peak concentration with a time-related decay rate as the dust moves past the sampling locations. The respirable dust concentrations and peak levels were notably diminished as the dust cloud was transported, diluted, and diffused by the wind over the 100 ft distance from the road. Individual truck concentrations and peak levels measured next to the dry road surface test section were quite variable and dependent on wind conditions, particularly wind direction, with respect to reaching the sampling location. The vast majority of the fugitive airborne dust generated from unpaved and untreated haulage roads was non-respirable. 6 figs.

  15. Dissecting Japan's Dengue Outbreak in 2014

    PubMed Central

    Quam, Mikkel B.; Sessions, October; Kamaraj, Uma Sangumathi; Rocklöv, Joacim; Wilder-Smith, Annelies

    2016-01-01

    Despite Japan's temperate climate, a dengue outbreak occurred in Tokyo for the first time in over 70 years in 2014. We dissected this dengue outbreak based on phylogenetic analysis, travel interconnectivity, and environmental drivers for dengue epidemics. Comparing the available dengue virus 1 (DENV1) E gene sequence from this outbreak with 3,282 unique DENV1 sequences in National Center for Biotechnology Information suggested that the DENV might have been imported from China, Indonesia, Singapore, or Vietnam. With travelers arriving into Japan, Guangzhou (China) may have been the source of DENV introduction, given that Guangzhou also reported a large-scale dengue outbreak in 2014. Coinciding with the 2014 outbreak, Tokyo's climate conditions permitted the amplification of Aedes vectors and the annual peak of vectorial capacity. Given suitable vectors and climate conditions in addition to increasing interconnectivity with endemic areas of Asia, Tokyo's 2014 outbreak did not come as a surprise and may foretell more to come. PMID:26711518

  16. Dissecting Japan's Dengue Outbreak in 2014.

    PubMed

    Quam, Mikkel B; Sessions, October; Kamaraj, Uma Sangumathi; Rocklöv, Joacim; Wilder-Smith, Annelies

    2016-02-01

    Despite Japan's temperate climate, a dengue outbreak occurred in Tokyo for the first time in over 70 years in 2014. We dissected this dengue outbreak based on phylogenetic analysis, travel interconnectivity, and environmental drivers for dengue epidemics. Comparing the available dengue virus 1 (DENV1) E gene sequence from this outbreak with 3,282 unique DENV1 sequences in National Center for Biotechnology Information suggested that the DENV might have been imported from China, Indonesia, Singapore, or Vietnam. With travelers arriving into Japan, Guangzhou (China) may have been the source of DENV introduction, given that Guangzhou also reported a large-scale dengue outbreak in 2014. Coinciding with the 2014 outbreak, Tokyo's climate conditions permitted the amplification of Aedes vectors and the annual peak of vectorial capacity. Given suitable vectors and climate conditions in addition to increasing interconnectivity with endemic areas of Asia, Tokyo's 2014 outbreak did not come as a surprise and may foretell more to come. PMID:26711518

  17. Impact of Radiatively Interactive Dust Aerosols in the NASA GEOS-5 Climate Model: Sensitivity to Dust Particle Shape and Refractive Index

    NASA Technical Reports Server (NTRS)

    Colarco, Peter R.; Nowottnick, Edward Paul; Randles, Cynthia A.; Yi, Bingqi; Yang, Ping; Kim, Kyu-Myong; Smith, Jamison A.; Bardeen, Charles D.

    2013-01-01

    We investigate the radiative effects of dust aerosols in the NASA GEOS-5 atmospheric general circulation model. GEOS-5 is improved with the inclusion of a sectional aerosol and cloud microphysics module, the Community Aerosol and Radiation Model for Atmospheres (CARMA). Into CARMA we introduce treatment of the dust and sea salt aerosol lifecycle, including sources, transport evolution, and sinks. The aerosols are radiatively coupled to GEOS-5, and we perform a series of multi-decade AMIP-style simulations in which dust optical properties (spectral refractive index and particle shape distribution) are varied. Optical properties assuming spherical dust particles are from Mie theory, while those for non-spherical shape distributions are drawn from a recently available database for tri-axial ellipsoids. The climatologies of the various simulations generally compare well to data from the MODIS, MISR, and CALIOP space-based sensors, the ground-based AERONET, and surface measurements of dust deposition and concentration. Focusing on the summertime Saharan dust cycle we show significant variability in our simulations resulting from different choices of dust optical properties. Atmospheric heating due to dust enhances surface winds over important Saharan dust sources, and we find a positive feedback where increased dust absorption leads to increased dust emissions. We further find that increased dust absorption leads to a strengthening of the summertime Hadley cell circulation, increasing dust lofting to higher altitudes and strengthening the African Easterly Jet. This leads to a longer atmospheric residence time, higher altitude, and generally more northward transport of dust in simulations with the most absorbing dust optical properties. We find that particle shape, although important for radiance simulations, is a minor effect compared to choices of refractive index, although total atmospheric forcing is enhanced by greater than 10 percent for simulations incorporating a

  18. Africans in America.

    ERIC Educational Resources Information Center

    Hart, Ayanna; Spangler, Earl

    This book introduces African-American history and culture to children. The first Africans in America came from many different regions and cultures, but became united in this country by being black, African, and slaves. Once in America, Africans began a long struggle for freedom which still continues. Slavery, the Civil War, emancipation, and the…

  19. African Outreach Workshop 1974.

    ERIC Educational Resources Information Center

    Schmidt, Nancy J.

    This report discusses the 1974 African Outreach Workshop planned and coordinated by the African Studies Program at the University of Illinois at Urbana-Champaign. Its major aim was to assist teachers in developing curriculum units on African using materials available in their local community. A second aim was for the African Studies Program to…

  20. Soluble iron dust export in the high altitude Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Ravelo-Pérez, L. M.; Rodríguez, S.; Galindo, L.; García, M. I.; Alastuey, A.; López-Solano, J.

    2016-05-01

    Every summer huge amounts of desert dust particles are exported from the hyperarid subtropical Sahara to the North Atlantic the so-called Saharan Air Layer (SAL), a dry, warm and dust-laden corridor that expands from the North African coast (1-5 km.a.s.l.) to the Americas above the marine boundary layer. Because of the potential impact of the dust deposited on the ocean on marine biogeochemistry and climate, we studied the Fe solubility (in seawater) of atmospheric aerosols samples directly collected in the SAL off the North African coast, i.e. the fresh aerosols recently exported from the Sahara in the SAL. The aerosol sampling was performed at ∼2400 m.a.s.l. in Izaña observatory in Tenerife island. In the total aerosols, we found low Fe concentrations and high fractional Fe solubility (FFS ∼2%) in the North Atlantic free troposphere airflows and high Fe concentrations and low FFS (∼0.7%) within the SAL; the resulting FFS versus total dust (or total Fe) plot shows a hyperbolic trend attributed to the conservative mixing of 'fine combustion aerosols' and 'lithogenic mineral dust'. We then focused on the soluble Fe in the SAL. Our results indicate that ∼70% of soluble Fe is associated with the dissolution of submicron dust particles, probably involving Fe-bearing clays. We found a FFS of submicron dust (∼6%) higher than that typically observed in submicron particles of soil dust samples (<1%). The correlation between FFS and the ammonium-sulphate/dust ratio and the low variability in the Fe/Al ratio in the dust samples, suggests that the increase in the FFS of submicron dust aerosols (with respect to soil dust particles) may be related to the presence of acid pollutants mixed with dust. Previous studies had focused on dust processing and changes of Fe solubility during the trans-Atlantic transport of dust in the SAL. We found that submicron dust exported off the coast of North Africa may have already experienced acid processing over the Sahara, i

  1. DUST FORMATION IN MACRONOVAE

    SciTech Connect

    Takami, Hajime; Ioka, Kunihito; Nozawa, Takaya E-mail: kunihito.ioka@kek.jp

    2014-07-01

    We examine dust formation in macronovae (as known as kilonovae), which are the bright ejecta of neutron star binary mergers and one of the leading sites of r-process nucleosynthesis. In light of information about the first macronova candidate associated with GRB 130603B, we find that dust grains of r-process elements have difficulty forming because of the low number density of the r-process atoms, while carbon or elements lighter than iron can condense into dust if they are abundant. Dust grains absorb emission from ejecta with an opacity even greater than that of the r-process elements, and re-emit photons at infrared wavelengths. Such dust emission can potentially account for macronovae without r-process nucleosynthesis as an alternative model. This dust scenario predicts a spectrum with fewer features than the r-process model and day-scale optical-to-ultraviolet emission.

  2. Bright Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    9 June 2004 Martian dust devils sometimes disrupt thin coatings of surface dust to create dark streak patterns on the surface. However, not all dust devils make streaks, and not all dust devil streaks are dark. In Syria Planum, the streaks are lighter than the surrounding plains. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example from Syria near 8.8oS, 103.6oW. The thin coating of surface dust in this region is darker than the substrate beneath it. This is fairly unusual for Mars, because most dust is bright. This image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.

  3. The Role of the Polio Program Infrastructure in Response to Ebola Virus Disease Outbreak in Nigeria 2014

    PubMed Central

    Vaz, Rui G.; Mkanda, Pascal; Banda, Richard; Komkech, William; Ekundare-Famiyesin, Olubowale O.; Onyibe, Rosemary; Abidoye, Sunday; Nsubuga, Peter; Maleghemi, Sylvester; Hannah-Murele, Bolatito; Tegegne, Sisay G.

    2016-01-01

    Background. The current West African outbreak of the Ebola virus disease (EVD) began in Guinea in December 2013 and rapidly spread to Liberia and Sierra Leone. On 20 July 2014, a sick individual flew into Lagos, Nigeria, from Monrovia, Liberia, setting off an outbreak in Lagos and later in Port Harcourt city. The government of Nigeria, supported by the World Health Organization and other partners, mounted a response to the outbreak relying on the polio program experiences and infrastructure. On 20 October 2014, the country was declared free of EVD. Methods. We examined the organization and operations of the response to the 2014 EVD outbreak in Nigeria and how experiences and support from the country's polio program infrastructure accelerated the outbreak response. Results. The deputy incident manager of the National Polio Emergency Operations Centre was appointed the incident manager of the Ebola Emergency Operations Centre (EEOC), the body that coordinated and directed the response to the EVD outbreak in the country. A total of 892 contacts were followed up, and blood specimens were collected from 61 persons with suspected EVD and tested in designated laboratories. Of these, 19 (31%) were positive for Ebola, and 11 (58%) of the case patients were healthcare workers. The overall case-fatality rate was 40%. EVD sensitization and training were conducted during the outbreak and for 2 months after the outbreak ended. The World Health Organization deployed its surveillance and logistics personnel from non–Ebola-infected states to support response activities in Lagos and Rivers states. Conclusions. The support from the polio program infrastructure, particularly the coordination mechanism adopted (the EEOC), the availability of skilled personnel in the polio program, and lessons learned from managing the polio eradication program greatly contributed to the speedy containment of the 2014 EVD outbreak in Nigeria. PMID:26908718

  4. Adapting MODIS Dust Mask Algorithm to Suomi NPP VIIRS for Air Quality Applications

    NASA Astrophysics Data System (ADS)

    Ciren, P.; Liu, H.; Kondragunta, S.; Laszlo, I.

    2012-12-01

    Despite pollution reduction control strategies enforced by the Environmental Protection Agency (EPA), large regions of the United States are often under exceptional events such as biomass burning and dust outbreaks that lead to non-attainment of particulate matter standards. This has warranted the National Weather Service (NWS) to provide smoke and dust forecast guidance to the general public. The monitoring and forecasting of dust outbreaks relies on satellite data. Currently, Aqua/MODIS (MODerate resolution Imaging Spectrometer) and Terra/MODIS provide measurements needed to derive dust mask and Aerosol Optical Thickness (AOT) products. The newly launched Suomi NPP VIIRS (Visible/Infrared Imaging Radiometer Suite) instrument has a Suspended Matter (SM) product that indicates the presence of dust, smoke, volcanic ash, sea salt, and unknown aerosol types in a given pixel. The algorithm to identify dust is different over land and ocean but for both, the information comes from AOT retrieval algorithm. Over land, the selection of dust aerosol model in the AOT retrieval algorithm indicates the presence of dust and over ocean a fine mode fraction smaller than 20% indicates dust. Preliminary comparisons of VIIRS SM to CALIPSO Vertical Feature Mask (VFM) aerosol type product indicate that the Probability of Detection (POD) is at ~10% and the product is not mature for operational use. As an alternate approach, NESDIS dust mask algorithm developed for NWS dust forecast verification that uses MODIS deep blue, visible, and mid-IR channels using spectral differencing techniques and spatial variability tests was applied to VIIRS radiances. This algorithm relies on the spectral contrast of dust absorption at 412 and 440 nm and an increase in reflectivity at 2.13 μm when dust is present in the atmosphere compared to a clear sky. To avoid detecting bright desert surface as airborne dust, the algorithm uses the reflectances at 1.24 μm and 2.25 μm to flag bright pixels. The

  5. Regional modeling of Saharan dust events using the RegCM model

    NASA Astrophysics Data System (ADS)

    Santese, M.; Perrone, M. R.; Zakey, A.

    2009-04-01

    As one of the major components of the atmospheric aerosol, mineral dust plays an important role in the Earth's climate system. Dust has been found to redistribute the radiative energy from the surface to the dust loaded atmospheric column by cooling the surface while heating the dust layer. The resulting stabilizing effect on the vertical structure of the atmosphere can affect cloud formation and the dust production itself. In addition, dust may change the size number of cloud condensation nuclei (CCN) and thus the optical and precipitation properties of clouds. All these impacts are difficult to quantify due to the highly variable spatio-temporal distribution of mineral dust and uncertainties determining its optical and physicochemical properties (IPCC 2001). The distribution of dust has been modeled in many studies using general circulation models (GCMs). However, because the aerosol effects are especially important at the regional scale, the recent development of high-resolution regional climate models (RCMs) offers useful tools to assess the regional impacts of aerosols. Compared to global climate models (GCMs), the relatively high-resolution and detailed physical parameterizations by RCMs are particularly suitable to describe the complexity of aerosol processes (Solmon et al., 2006). Furthermore, the results from regional models are well suited for comparisons with measurements of individual events. Dust radiative effects on climate are likely to be especially important at the regional scale, thus RCMs can be particularly useful tools to investigate the regional climate effects of dust outbreaks (Zakey et al., 2006). In this work, we will use the regional climate model RegCM (Version 3.1), developed at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, to investigate dust event impacts over Mediterranean sites. The Sahara desert is the largest dust source on Earth, providing at least half of the emitted dust (Washington et al., 2003

  6. Response of mesoscale convective system (MCS) and cold pool formation to dust-radiative effects

    NASA Astrophysics Data System (ADS)

    Waylonis, M. T.; Chen, S. H.

    2014-12-01

    This study examines the role of dust in the development of a mesoscale convective system (MCS) over the central-west Sahara, and how cold pools from the MCS feedback to dust emissions. Few studies have simulated the direct-radiative effects of dust on cloud development. Moderate Resolution Imaging Spectrometer (MODIS) and Multi-angle Imaging Spectrometer (MISR) Retrieved aerosol optical depth and Meteosat Second Generation dust enhancement product were used to examine a dust outbreak that occurred between 13 and 15 August 2005 and revealed that an moist intrusion into the Sahara caused a MCS to form and resulted in dust emission due to cold pool outflow from the MCS. A dust model based on the Weather Research and Forecasting model was developed to include dust emissions, transport, dry and moist deposition, and radiation interactions and was used to simulate the case. Dust-radiation interactions were found to enhance convective strength through low-level heating, which increased convective available potential energy and low-level convergence. The increased intensity of the convection led to stronger and more widespread cold pool formation, which in turn emitted more dust into the atmosphere.

  7. Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 8 May 2002) The Science This image, centered near 50.0 S and 17.7 W displays dust devil tracks on the surface. Most of the lighter portions of the image likely have a thin veneer of dust settled on the surface. As a dust devil passes over the surface, it acts as a vacuum and picks up the dust, leaving the darker substrate exposed. In this image there is a general trend of many of the tracks running from east to west or west to east, indicating the general wind direction. There is often no general trend present in dust devil tracks seen in other images. The track patterns are quite ephemeral and can completely change or even disappear over the course of a few months. Dust devils are one of the mechanisms that Mars uses to constantly pump dust into the ubiquitously dusty atmosphere. This atmospheric dust is one of the main driving forces of the present Martian climate. The Story Vrrrrooooooooom. Think of a tornado, the cartoon Tasmanian devil, or any number of vacuum commercials that powerfully suck up swirls of dust and dirt. That's pretty much what it's like on the surface of Mars a lot of the time. Whirlpools of wind called

  8. Cometary dust composition

    NASA Technical Reports Server (NTRS)

    Gehrz, R. D.; Hanner, M. S.

    1988-01-01

    The earth based measurements and in situ sampling of Comet Halley have provided new data about the chemical composition of cometary grains. Recent progress in laboratory studies of interplanetary dust particles (IDPs) complement the comet data, allowing inferences about the mineralogy and physical structure of the comet dust to be drawn from the observed elemental composition and infrared spectra. The in situ dust composition measurements at Halley, the composition of IDPs and their relation to comet dust, and the origin of the 3.4 micron hydrocarbon feature is discussed. Related discussion is also presented on aromatic components in comets and the 3.4 micron feature. These topics are briefly summarized.

  9. Operational Dust Prediction

    NASA Technical Reports Server (NTRS)

    Benedetti, Angela; Baldasano, Jose M.; Basart, Sara; Benincasa, Francesco; Boucher, Olivier; Brooks, Malcolm E.; Chen, Jen-Ping; Colarco, Peter R.; Gong, Sunlin; Huneeus, Nicolas; Jones, Luke; Lu, Sarah; Menut, Laurent; Morcrette, Jean-Jacques; Mulcahy, Jane; Nickovic, Slobodan; Garcia-Pando, Carlos P.; Reid, Jeffrey S.; Sekiyama, Thomas T.; Tanaka, Taichu Y.; Terradellas, Enric; Westphal, Douglas L.; Zhang, Xiao-Ye; Zhou, Chun-Hong

    2014-01-01

    Over the last few years, numerical prediction of dust aerosol concentration has become prominent at several research and operational weather centres due to growing interest from diverse stakeholders, such as solar energy plant managers, health professionals, aviation and military authorities and policymakers. Dust prediction in numerical weather prediction-type models faces a number of challenges owing to the complexity of the system. At the centre of the problem is the vast range of scales required to fully account for all of the physical processes related to dust. Another limiting factor is the paucity of suitable dust observations available for model, evaluation and assimilation. This chapter discusses in detail numerical prediction of dust with examples from systems that are currently providing dust forecasts in near real-time or are part of international efforts to establish daily provision of dust forecasts based on multi-model ensembles. The various models are introduced and described along with an overview on the importance of dust prediction activities and a historical perspective. Assimilation and evaluation aspects in dust prediction are also discussed.

  10. Dust Transport, Deposition and Radiative Effects Observed from MODIS

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Koren, I.; Remer, L. A.; Tanre, D.; Ginoux, P.; Fan, S.

    2003-01-01

    Carlson (1977) used satellite (AVHRR) observation of dust episodes 3 estimate that 90 tg of dust are emitted from Africa (0-30 N) to the Atlantic Ocean between June and August. MODIS systematic measurements of aerosol optical thickness (AOT) and the fraction of the AOT (f) due to the fine mode (see Remer et al abstract), are used to derive the column concentration, flux and deposition of African dust over the Atlantic Ocean. The main data set is for 2001 but the results are consistent with MODIS measurements from 2002. The analysis first determines the properties of maritime baseline aerosol (AOT=0.06, f=0.5); followed by linear scaling of the dust AOT and the anthropogenic AOT, based on MODIS measured values of the fraction "f" being 0.9 for anthropogenic aerosol and 0.5 for dust. NCEP winds are used in the analysis and are evaluated against observed dust movements between the Terra and Aqua passes (see Koren et al. abstract). Monthly values of dust transport and deposition are calculated. Preliminary results show that 280 tg of dust are emitted annually from Africa to the Atlantic Ocean between 20s and 30N, with 40 tg returning to Africa and Europe between 30N and 50N. 85 tg reach the Americas, with 130-150 tg are deposited in the Atlantic Ocean. The results are compared with dust transport models that indicate 110-230 tg of dust being deposited in the Ocean. It is interesting to note that the early estimates of Carlson (1977) and Carlson & Prosper0 (1972) are very close to our estimate from MODIS of 100 tg for the same latitude range and monthly period.

  11. Four-year study of Middle East and Sahara dust intrusions in terms of particle lidar ratio: Observations with lidar and sun/sky photometer over Limassol, Cyprus

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The remote sensing station of the Cyprus University of Technology (CUT) at Limassol (34.7oN, 33oE, 50m above sea level a.s.l.) is located in the southeast part of the Mediterranean (150km south of Turkey and 250km west of Syria) and dust aerosol components from Sahara and Middle East deserts comprise the major sources of dust layers in the study area. The CUT station is equipped with a European Aerosol Research Lidar Network (EARLINET) lidar and Aerosol Robotic Network (AERONET) sun/sky photometer. The combined database of four years (2010 -2013) of observations was used to compare extinction-to-backscatter ratios (lidar ratios) for dust from Middle East and Sahara deserts. For the first time, a long-term lidar study on the lidar ratio of Middle East desert dust is presented. The results are compared with respective findings for Saharan dust outbreaks. The Limassol lidar station at the island of Cyprus in the eastern Mediterranean Sea is unique because it is the only site of the EARLINET which is influenced by a statistically significant number (5-7) of Middle East dust outbreaks each year as well as by numerous Saharan dust outbreaks (>10 per year). For this analysis we considered 17 major dust outbreaks from the Middle East and 32 dust outbreaks from North Africa. Simultaneous EARLINET lidar and AERONET photometer observations were conducted at Limassol almost day by day over the four year period from April 2010 to December 2013. The quality of the retrieval is checked within a case study by comparing the results with respective Raman lidar solutions for particle backscatter, extinction, and lidar ratio. The applied combined lidar/photometer retrievals corroborate recent findings regarding the difference between Middle East and Saharan desert dust lidar ratios. We found values from 44-65 sr with a mean value of 52.7 sr for Saharan dust and from 35-46 sr with a mean value of 41.1 sr for Middle East dust. The presented data analysis, however, also demonstrates the

  12. Whither Cometary Dust?

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  13. Lack of Comprehensive Outbreak Detection in Hospitals.

    PubMed

    Baker, Meghan A; Huang, Susan S; Letourneau, Alyssa R; Kaganov, Rebecca E; Peeples, Jennifer R; Drees, Marci; Platt, Richard; Yokoe, Deborah S

    2016-04-01

    Timely identification of outbreaks of hospital-associated infections is needed to implement control measures and minimize impact. Survey results from 33 hospitals indicated that most hospitals lacked a formal cluster definition and all targeted a very limited group of prespecified pathogens. Standardized, statistically based outbreak detection could greatly improve current practice. PMID:26996060

  14. Molecular Diagnostic Analysis of Outbreak Scenarios

    ERIC Educational Resources Information Center

    Morsink, M. C.; Dekter, H. E.; Dirks-Mulder, A.; van Leeuwen, W. B.

    2012-01-01

    In the current laboratory assignment, technical aspects of the polymerase chain reaction (PCR) are integrated in the context of six different bacterial outbreak scenarios. The "Enterobacterial Repetitive Intergenic Consensus Sequence" (ERIC) PCR was used to analyze different outbreak scenarios. First, groups of 2-4 students determined optimal…

  15. Selection tool for foodborne norovirus outbreaks.

    PubMed

    Verhoef, Linda P B; Kroneman, Annelies; van Duynhoven, Yvonne; Boshuizen, Hendriek; van Pelt, Wilfrid; Koopmans, Marion

    2009-01-01

    Detection of pathogens in the food chain is limited mainly to bacteria, and the globalization of the food industry enables international viral foodborne outbreaks to occur. Outbreaks from 2002 through 2006 recorded in a European norovirus surveillance database were investigated for virologic and epidemiologic indicators of food relatedness. The resulting validated multivariate logistic regression model comparing foodborne (n = 224) and person-to-person (n = 654) outbreaks was used to create a practical web-based tool that can be limited to epidemiologic parameters for nongenotyping countries. Non-genogroup-II.4 outbreaks, higher numbers of cases, and outbreaks in restaurants or households characterized (sensitivity = 0.80, specificity = 0.86) foodborne outbreaks and reduced the percentage of outbreaks requiring source-tracing to 31%. The selection tool enabled prospectively focused follow-up. Use of this tool is likely to improve data quality and strain typing in current surveillance systems, which is necessary for identification of potential international foodborne outbreaks. PMID:19116046

  16. Incentives for Reporting Infectious Disease Outbreaks

    ERIC Educational Resources Information Center

    Malani, Anup; Laxminarayan, Ramanan

    2011-01-01

    The global spread of diseases such as swine flu and SARS highlights the difficult decision governments face when presented with evidence of a local outbreak. Reporting the outbreak may bring medical assistance but is also likely to trigger trade sanctions by countries hoping to contain the disease. Suppressing the information may avoid trade…

  17. WATERBORNE DISEASE OUTBREAKS, 1986-1988

    EPA Science Inventory

    From 1986 to 1988, 24 states and Puerto Rico reported 50 outbreaks of illness due to water that people intended to drink, affecting 25,846 persons. he protozoal parasite Giardia lamblia was the agent most commonly implicated in outbreaks, as it has been for the last 10 years; man...

  18. The Nature of Interstellar Dust

    NASA Technical Reports Server (NTRS)

    Huss, G. R.

    2003-01-01

    The STARDUST mission is designed to collect dust the coma of comet Wild 2 and to collect interstellar dust on a second set of collectors. We have a reasonable idea of what to expect from the comet dust collection because the research community has been studying interplanetary dust particles for many years. It is less clear what we should expect from the interstellar dust. This presentation discusses what we might expect to find on the STARDUST interstellar dust collector.

  19. Combustible dust tests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugar dust explosion in Georgia on February 7, 2008 killed 14 workers and injured many others (OSHA, 2009). As a consequence of this explosion, OSHA revised its Combustible Dust National Emphasis (NEP) program. The NEP targets 64 industries with more than 1,000 inspections and has found more tha...

  20. Pathfinder Spies Dust Devils

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This set of images from NASA's 1997 Pathfinder mission highlight the dust devils that gust across the surface of Mars. The right image shows the dusty martian sky as our eye would see it. The left image has been enhanced to expose the dust devils that lurk in the hazy sky.

  1. Dust resuspension without saltation

    PubMed Central

    Loosmore, Gwen A.; Hunt, James R.

    2010-01-01

    Wind resuspension (or entrainment) provides a source of dust and contaminants for the atmosphere. Conventional wind erosion models parameterize dust resuspension flux with a threshold velocity or with a horizontal abrasion flux; in the absence of abrasion the models assume dust flux is transient only. Our experiments with an uncrusted, fine material at relative humidities exceeding 40% show a long-term steady dust flux in the absence of abrasion, which fits the approximate form: Fd = 3.6(u*)3, where Fd is the dust flux (in μg/m2 s), and u* is the friction velocity (in m/s). These fluxes are generally too small to be significant sources of dust in most models of dust emission. However, they provide a potential route to transport contaminants into the atmosphere. In addition, dust release is substantial during the initial transient phase. Comparison with field data suggests that the particle friction Reynolds number may prove a better parameter than u* for correlating fluxes and understanding the potential for abrasion. PMID:20336175

  2. Toxicity of lunar dust

    NASA Astrophysics Data System (ADS)

    Linnarsson, Dag; Carpenter, James; Fubini, Bice; Gerde, Per; Karlsson, Lars L.; Loftus, David J.; Prisk, G. Kim; Staufer, Urs; Tranfield, Erin M.; van Westrenen, Wim

    2012-12-01

    The formation, composition and physical properties of lunar dust are incompletely characterised with regard to human health. While the physical and chemical determinants of dust toxicity for materials such as asbestos, quartz, volcanic ashes and urban particulate matter have been the focus of substantial research efforts, lunar dust properties, and therefore lunar dust toxicity may differ substantially. In this contribution, past and ongoing work on dust toxicity is reviewed, and major knowledge gaps that prevent an accurate assessment of lunar dust toxicity are identified. Finally, a range of studies using ground-based, low-gravity, and in situ measurements is recommended to address the identified knowledge gaps. Because none of the curated lunar samples exist in a pristine state that preserves the surface reactive chemical aspects thought to be present on the lunar surface, studies using this material carry with them considerable uncertainty in terms of fidelity. As a consequence, in situ data on lunar dust properties will be required to provide ground truth for ground-based studies quantifying the toxicity of dust exposure and the associated health risks during future manned lunar missions.

  3. The lunar dust pendulum

    NASA Astrophysics Data System (ADS)

    Collier, Michael R.; Farrell, William M.; Stubbs, Timothy J.

    2013-07-01

    An analytic model for the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum is presented. It is shown that the dust grain executes oscillatory trajectories, and an expression is derived for the period of oscillation. Simulations used to verify the analytic expression also show that because the trajectories are unstable, dust grains are either ejected from the crater's vicinity or deposited into the crater forming "dust ponds." The model also applies to other airless bodies in the solar system, such as asteroids, and predicts that under certain conditions, particularly near lunar sunset, oscillating dust "canopies" or "swarms" will form over negatively charged craters.

  4. Dust escape from Io

    NASA Astrophysics Data System (ADS)

    Flandes, Alberto

    2004-08-01

    The Dust ballerina skirt is a set of well defined streams composed of nanometric sized dust particles that escape from the Jovian system and may be accelerated up to >=200 km/s. The source of this dust is Jupiter's moon Io, the most volcanically active body in the Solar system. The escape of dust grains from Jupiter requires first the escape of these grains from Io. This work is basically devoted to explain this escape given that the driving of dust particles to great heights and later injection into the ionosphere of Io may give the particles an equilibrium potential that allow the magnetic field to accelerate them away from Io. The grain sizes obtained through this study match very well to the values required for the particles to escape from the Jovian system.

  5. Lunar Dust Mitigation Screens

    NASA Astrophysics Data System (ADS)

    Knutson, Shawn; Holloway, Nancy

    With plans for the United States to return to the moon, and establish a sustainable human presence on the lunar surface many issues must be successfully overcome. Lunar dust is one of a number of issues with the potential to create a myriad of problems if not adequately addressed. Samples of dust brought back from Apollo missions show it to be soft, yet sharp and abrasive. The dust consists of a variety of morphologies including spherical, angular blocks, shards, and a number of irregular shapes. One of the main issues with lunar dust is its attraction to stick to anything it comes in contact with (i.e. astronauts, equipment, habitats, etc.). Ionized radiation from the sun strikes the moon's surface and creates an electrostatic charge on the dust. Further, the dust harbors van der Waals forces making it especially difficult to separate once it sticks to a surface. During the Apollo missions, it was discovered that trying to brush the lunar dust from spacesuits was not effective, and rubbing it caused degradation of the suit material. Further, when entering the lunar module after moonwalks, the astronauts noted that the dust was so prolific inside the cabin that they inhaled and ingested it, causing at least one of them, Harrison "Jack" Schmidt, to report irritation of the throat and lungs. It is speculated that the dust could also harm an astronaut's nervous and cardiovascular systems, especially during an extended stay. In addition to health issues, the dust can also cause problems by scouring reflective coatings off of thermal blankets, and roughening surfaces of windows and optics. Further, panels on solar cells and photovoltaics can also be compromised due to dust sticking on the surfaces. Lunar dust has the capacity to penetrate seals, interfere with connectors, as well as mechanisms on digging machines, all of which can lead to problems and failure. To address lunar dust issues, development of electrostatic screens to mitigate dust on sur-faces is currently

  6. Loire Dust Devil

    NASA Technical Reports Server (NTRS)

    2005-01-01

    25 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an active dust devil making its way across the rugged terrain of the Loire Vallis system. The dust devil, seen as a fuzzy, nearly-circular bright feature near the center of the picture, is casting a shadow toward the right/upper right (east/northeast). Unlike some martian dust devils, this one did not make a dark streak on the ground. Many more dust devils occur on Mars than there are dust devil streaks observed on the planet's surface.

    Location near: 18.2oS, 16.5oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  7. Isidis Dust Devil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    10 March 2004 This arrow in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image points to an active dust devil observed in Isidis Planitia near 18.3oN, 268.9oW. The columnar shadow of the dust devil is visible, as is a pencil-thin (at least, pencil-thin at the scale of the image) line created by the vortex as it disrupted the dust that coats the surface. The streak indicates that the dust devil had already traveled more than 3 kilometers (1.9 miles), over craters, large ripples, and ridges, before the MOC took this picture. The dust devil was moving from the northeast (upper right) toward the southwest (lower left). Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.

  8. Clear Sky Column Closure Studies of Urban-Marine and Mineral-Dust Aerosols Using Aircraft, Ship, Satellite and Ground-Based Measurements in ACE-2

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Russell, Philip B.; Livingston, John M.; Gasso, Santiago; Hegg, Dean A.; Collins, Donald R.; Flagan, Richard C.; Seinfeld, John H.; Oestroem, Elisabeth; Noone, Kevin J.; Durkee, Philip A.; Jonsson, Haflidi H.; Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Formenti, Paola; Andreae, Meinrat O.; Kapustin, Vladimir N.; Bates, Timothy S.; Quinn, Patricia K.

    2000-01-01

    As part of the second Aerosol Characterization Experiment (ACE-2), European urban-marine and African mineral-dust aerosols were measured aboard the Pelican aircraft, the Research Vessel Vodyanitskiy from the ground and from satellites.

  9. Pertussis Outbreak, Southeastern Minnesota, 2012

    PubMed Central

    Theofiles, Alexander G.; Cunningham, Scott A.; Chia, Nicholas; Jeraldo, Patricio R.; Quest, Daniel J.; Mandrekar, Jayawant N.; Patel, Robin

    2015-01-01

    Objective To describe clinical and laboratory findings from the 2012 southeastern Minnesota pertussis outbreak. Patients and Methods Patients were selected for 2 parts of the study. In the first part, nasopharyngeal swabs from a convenience sample of 265 unique patients were used for both the clinician-requested polymerase chain reaction (PCR) test and culture. B pertussis isolates were tested for macrolide susceptibility and typed using whole genome sequencing and pulsed-field gel electrophoresis. Pertactin gene sequences were analyzed to identify pertactin-deficient B pertussis. In the second part, all patients seen at Mayo Clinic in Rochester, Minnesota, who had PCR results positive for Bordetella pertussis or Bordetella parapertussis between January 1, 2012, and December 31, 2012, were analyzed for patient demographic features and vaccination records. Results One hundred sixty patients had results positive for B pertussis, and 21 patients had results positive for B parapertussis. Among the 265 swabs cultured, B pertussis was detected by both culture and PCR in 11. One swab was positive for B pertussis by culture alone, and 13 were positive by PCR alone. Polymerase chain reaction detected B pertussis more frequently than did culture (P=.001). No macrolide resistance was detected. All 12 isolates tested had an altered pertactin gene, including 9 with a signal sequence deletion, 2 with insertion sequence disruptions, and 1 with a premature stop codon. Nine and 3 isolates were pertactin types prn1 and prn2, respectively. Whole genome sequencing and pulsed-field gel electrophoresis detected the presence of multiple B pertussis strains. The mean age of patients with pertussis was younger than that of those without pertussis (15.6 and 25.5 years, respectively; P=.002). Compared with those whose test results were negative for B pertussis, fewer patients with positive results had received whole-cell pertussis vaccine (P=.02). In the subgroup who had received acellular

  10. STS-65 Earth observation of Bahama Islands with dust pall, taken from OV-102

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During STS-65 a significant dust pall that originated in western Africa was recorded by a series of low oblique color photographs as it continued its westward trek across the Atlantic Ocean and then the Caribbean Sea and the Gulf of Mexico area. This particular view captures the northern edge of the dust, positioned just slightly north of the Bahama Islands. This major transport of African dust to the western hemisphere has been recorded periodically by other Shuttle astronauts and earlier Shuttle missions. Scientifically, there is evidence that some of this African dust even reaches the Amazon rainforest and serves as a source of airborne nutrients for rainforest vegetation. This photograph was taken aboard Columbia, Orbiter Vehicle (OV) 102.

  11. Sequential Outbreaks Due to a New Strain of Neisseria Meningitidis Serogroup C in Northern Nigeria, 2013-14

    PubMed Central

    Funk, Anna; Uadiale, Kennedy; Kamau, Charity; Caugant, Dominique A.; Ango, Umar; Greig, Jane

    2014-01-01

    Background Neisseria meningitidis serogroup C (NmC) outbreaks occur infrequently in the African meningitis belt; the most recent report of an outbreak of this serogroup was in Burkina Faso, 1979. Médecins sans Frontières (MSF) has been responding to outbreaks of meningitis in northwest Nigeria since 2007 with no reported cases of serogroup C from 2007-2012. MenAfrivac®, a serogroup A conjugate vaccine, was first used for mass vaccination in northwest Nigeria in late 2012. Reactive vaccination using polysaccharide ACYW135 vaccine was done by MSF in parts of the region in 2008 and 2009; no other vaccination campaigns are known to have occurred in the area during this period. We describe the general characteristics of an outbreak due to a novel strain of NmC in Sokoto State, Nigeria, in 2013, and a smaller outbreak in 2014 in the adjacent state, Kebbi. Methods Information on cases and deaths was collected using a standard line-list during each week of each meningitis outbreak in 2013 and 2014 in northwest Nigeria. Initial serogroup confirmation was by rapid Pastorex agglutination tests. Cerebrospinal fluid (CSF) samples from suspected meningitis patients were sent to the WHO Reference Laboratory in Oslo, where bacterial isolates, serogrouping, antimicrobial sensitivity testing, genotype characterisation and real-time PCR analysis were performed. Results In the most highly affected outbreak areas, all of the 856 and 333 clinically suspected meningitis cases were treated in 2013 and 2014, respectively. Overall attack (AR) and case fatality (CFR) rates were 673/100,000 population and 6.8% in 2013, and 165/100,000 and 10.5% in 2014. Both outbreaks affected small geographical areas of less than 150km2 and populations of less than 210,000, and occurred in neighbouring regions in two adjacent states in the successive years. Initial rapid testing identified NmC as the causative agent. Of the 21 and 17 CSF samples analysed in Oslo, NmC alone was confirmed in 11 and 10

  12. Assessing the Performance of the Photovoltaic Cells on the Effects of Yellow Dust Events and Haze in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Choi, Jiyeon; Kim, Yong Pyo; Wee, DaeHyun

    2016-04-01

    We analyze the potential effects of the Asian yellow dust Events and haze on the performance of Korean photovoltaic systems. Particulate matters from the Asian yellow dust outbreaks in the deserts of Mongolia and northern China are typically transported to Korea. Haze is an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky. Hence, we conjecture that the effects of the Asian yellow dust and haze block the incident solar irradiance. The potential reduction of the solar spectral irradiance due to Asian yellow dust events and haze in Korea is investigated using a clear-sky spectral radiation model, and the performance of photovoltaic systems under reduced irradiance is estimated by using a simple analytic model representing typical photovoltaic cells. Comparison of photovoltaic performance under Asian dust events, haze and that under a clear condition is made to evaluate overall influence of the particulate air pollution, respectively.

  13. Characterization of mineral dust aerosols during the Saharan Dust Experiment (SHADE)

    NASA Astrophysics Data System (ADS)

    Léon, J.-F.; Tanré, D.; Haywood, J.; Pelon, J.; Kaufman, Y. J.

    2003-04-01

    Aerosols are known to be important in determining the Earth’s radiative balance. Dust aerosols are particularly interesting since, in addition to their scattering and absorbing properties that affect the solar radiation, they also perturb the terrestrial radiation. In addition, recent studies have shown that a significant proportion of mineral dust in the atmosphere may be of anthropogenic origin and therefore they may have an important role in climate change by exerting a significant radiative forcing. The Saharan Dust Experiment was designed to better determine the parameters that are relevant for computing the direct radiative effect of mineral dust. Two aircraft combining in situ measurements and remote sensing instruments were coordinated with satellite overpasses during the experiment which was based in Cape Verde during the period September 20-28, 2000. These in-situ and remotely sensed data provide valuable information on the microphysical, optical properties and radiative effects of a very large mineral dust outbreak with aerosol optical thickness up to 1.5. A new approach based on a synergy between active (lidar) and passive (spaceborne radiometer) remote sensing has been used to investigate the vertical structure of the dust plume. The retrieved profiles of extinction compare well with in situ aircraft measurements. Profiles derived from lidar measurements on September 25 highlight the presence of the so-called Saharan Air Layer, located between 2.2 and 4.5 km. Another dust layer within the sub-Saharan transition layer over the marine boundary layer is also observed. In this second layer, the effective radius of particles is significantly smaller than in the aloft layer. The trajectory analyses and the Total Mapping Ozone Spectrometer Aerosol Index suggest that the aerosols present at 1500m originates from West Mauritania. The higher aerosol layer originates from southern Algeria which confirms the difference of altitude of the dust transport

  14. Vector Competence of Selected African Mosquito (Diptera: Culicidae) Species for Rift Valley Fever Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outbreaks of Rift Valley fever (RVF) in Egypt, Yemen, and Saudi Arabia have indicated the potential for this disease to spread from its enzootic areas in sub-Saharan Africa. Because little is known about the potential for most African mosquito species to transmit RVF virus (RVFV), we conducted stud...

  15. Simulated changes in atmospheric dust in response to a Heinrich stadial

    NASA Astrophysics Data System (ADS)

    Murphy, Lisa N.; Clement, Amy C.; Albani, Samuel; Mahowald, Natalie M.; Swart, Peter; Arienzo, Monica M.

    2014-01-01

    stadials (HS), thought to be triggered by increased ice discharge in the high-latitude North Atlantic at glacial periods, resulted in large freshwater forcing that weakened the Atlantic Meridional Overturning Circulation (AMOC). These events are strongly expressed in paleoclimate records throughout the Atlantic basin and much of the tropics. Compared to the Last Glacial Maximum, recent proxy data suggest HS were much drier and dustier in large parts of the tropics. We use a global climate model coupled to a prognostic dust model to examine the response of dust to changes in climate during HS. Despite some significant changes in regional precipitation patterns in response to the simulated shift in the Intertropical Convergence Zone, we find that changes in winds have a larger effect on dust mobilization and deposition patterns than soil moisture or vegetation changes associated with a weaker AMOC. Although Europe was colder and drier during HS, the annual mean glaciogenic dust emission rate is lower because a southward shift in the Northern Hemisphere jet stream leads to weaker winds and less dust mobilization. The proximity of the westerly wind anomaly associated with the jet stream shift increases gustiness and dust mobilization over northwestern Africa and shifts the African Easterly Jet southward resulting in less African dust transport and deposition over the North Tropical Atlantic. Drier conditions over the Sahel region of North Africa, however, do not lead to increased dust mobilization in our model. When we perturb Sahelian soil characteristics, our results are in better agreement with proxies.

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

    NASA Astrophysics Data System (ADS)

    Jish Prakash, P.; Stenchikov, G.; Kalenderski, S.; Osipov, S.; Bangalath, H.

    2015-01-01

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

  17. Episode simulation of Asian dust storms with an air quality modeling system

    NASA Astrophysics Data System (ADS)

    Ge, Cui; Zhang, Meigen; Han, Zhiwei; Liu, Yanju

    2011-05-01

    A dust deflation module was developed and coupled with the air quality modeling system RAMS-CMAQ to simultaneously treat all the major tropospheric aerosols (i.e., organic and black carbons, sulfate, nitrate, ammonia, soil dust, and sea salt). Then the coupled system was applied to East Asia to simulate Asian dust aerosol generation, transport and dry/wet removal processes during 14-25 March 2002 when two strong dust storms occurred consecutively. To evaluate model performance and to analyze the observed features of dust aerosols over the East Asian region, model results were compared to concentrations of suspended particulate matter of 10 µm or less (PM10; 1-h intervals) at four remote Japanese stations and daily air pollution index (API) values for PM10 at four large Chinese cities. The modeled values were generally in good agreement with observed data, and the model reasonably reproduced two dust storm outbreaks and generally predicted the dust onset and cessation times at each observation site. In addition, hourly averaged values of aerosol optical thickness (AOT) were calculated and compared with observations at four Aerosol Robotic Network (AERONET) stations to assess the model's capability of estimating dust aerosol column burden. Analysis shows that modeled and observed AOT values were generally comparable and that the contribution of dust aerosols to AOT was significant only with regard to their source regions and their transport paths.

  18. Zika virus outbreak in Brazil.

    PubMed

    Heukelbach, Jorg; Alencar, Carlos Henrique; Kelvin, Alyson Ann; de Oliveira, Wanderson Kleber; Pamplona de Góes Cavalcanti, Luciano

    2016-02-01

    Zika virus (ZIKV) infection is spreading rapidly within the Americas after originating from an outbreak in Brazil. We describe the current ZIKV infection epidemic in Brazil and the neurological symptoms arising. First cases of an acute exanthematic disease were reported in Brazil's Northeast region at the end of 2014. In March 2015, autochthonous ZIKV was determined to be the causative agent of the exanthematic disease. As cases of neurological syndromes in regions where ZIKV, dengue and/or Chikungunya viruses co-circulate were reported, ZIKV was also identified in the cerebrospinal fluid of patients with acute neurological syndromes and previous exanthematic disease. By the end of September 2015, an increasing number of infants with small head circumference or microcephaly were noted in Brazil's Northeast which was estimated to be 29 cases between August and October. ZIKV was identified in blood and tissue samples of a newborn and in mothers who had given birth to infants with microcephaly and ophthalmological anomalies. In 2015, there were an estimated 440,000 - 1,300,000 Zika cases in Brazil. There have been 4,783 suspected cases of microcephaly, most of them in the Northeast of Brazil associated with 76 deaths. The Ministry of Health is intensifying control measures against the mosquito Aedes aegypti and implemented intensive surveillance actions. Further studies are needed to confirm the suspected association between ZIKV infection and microcephaly; to identify antiviral, immunotherapy, or prophylactic vaccine; to introduce diagnostic ELISA testing. Clinical and epidemiological studies must be performed to describe viral dynamics and expansion of the outbreak. PMID:26927450

  19. Complicated infectious coryza outbreaks in Argentina.

    PubMed

    Sandoval, V E; Terzolo, H R; Blackall, P J

    1994-01-01

    Seventeen complicated outbreaks of infectious coryza in layer, broiler-breeder, and broiler flocks were studied. In the layer flock outbreaks, drops in egg production of up to 35% were seen. In the broiler flocks and several of the layer flocks, losses due to persistent mortality and/or culling varied between 2 and 5%. Signs of infectious coryza in both layers and broiler-breeders were typical; in broilers, however, swollen head-like syndrome was seen. Except in one flock, no viral diseases were clinically or serologically detected. Excluding broiler-breeders, birds from most other flocks were serologically positive for Mycoplasma gallisepticum, and some were also positive for M. synoviae. Haemophilus paragallinarum was isolated from all of the outbreaks, but only as a pure culture in three outbreaks. Isolation of H. paragallinarum from sites such as liver, kidney, and particularly tarsal arthritis and ocular globes appears to be reported for the first time. Serovar A was isolated in eight outbreaks, serovar B in six, serovar C in one, and untypable serovars in two. The severity of these infectious coryza outbreaks may have been increased by concurrent salmonellosis, pasteurellosis, and mycoplasmosis, although under certain conditions H. paragallinarum is able to cause septicemia. Ten of the outbreaks occurred in birds vaccinated against infectious coryza; this may be due to the use of vaccines that do not provide protection against the types of H. paragallinarum that affect poultry in the region. PMID:7832727

  20. Dust in circumstellar disks

    NASA Astrophysics Data System (ADS)

    Rodmann, Jens

    2006-02-01

    This thesis presents observational and theoretical studies of the size and spatial distribution of dust particles in circumstellar disks. Using millimetre interferometric observations of optically thick disks around T Tauri stars, I provide conclusive evidence for the presence of millimetre- to centimetre-sized dust aggregates. These findings demonstrate that dust grain growth to pebble-sized dust particles is completed within less than 1 Myr in the outer disks around low-mass pre-main-sequence stars. The modelling of the infrared spectral energy distributions of several solar-type main-sequence stars and their associated circumstellar debris disks reveals the ubiquity of inner gaps devoid of substantial amounts of dust among Vega-type infrared excess sources. It is argued that the absence of circumstellar material in the inner disks is most likely the result of the gravitational influence of a large planet and/or a lack of dust-producing minor bodies in the dust-free region. Finally, I describe a numerical model to simulate the dynamical evolution of dust particles in debris disks, taking into account the gravitational perturbations by planets, photon radiation pressure, and dissipative drag forces due to the Poynting-Robertson effect and stellar wind. The validity of the code it established by several tests and comparison to semi-analytic approximations. The debris disk model is applied to simulate the main structural features of a ring of circumstellar material around the main-sequence star HD 181327. The best agreement between model and observation is achieved for dust grains a few tens of microns in size locked in the 1:1 resonance with a Jupiter-mass planet (or above) on a circular orbit.

  1. Black African Traditional Mathematics

    ERIC Educational Resources Information Center

    Zaslavsky, Claudia

    1970-01-01

    Discusses the traditional number systems and the origin of the number names used by several African peoples living south of the Sahara. Also included are limitations in African mathematical development, and possible topics for research. (RP)

  2. The May 2003 Extended Tornado Outbreak.

    NASA Astrophysics Data System (ADS)

    Hamill, Thomas M.; Schneider, Russell S.; Brooks, Harold E.; Forbes, Gregory S.; Bluestein, Howard B.; Steinberg, Michael; Meléndez, Daniel; Dole, Randall M.

    2005-04-01

    In May 2003 there was a very destructive extended outbreak of tornadoes across the central and eastern United States. More than a dozen tornadoes struck each day from 3 May to 11 May 2003. This outbreak caused 41 fatalities, 642 injuries, and approximately $829 million dollars of property damage. The outbreak set a record for most tornadoes ever reported in a week (334 between 4 10 May), and strong tornadoes (F2 or greater) occurred in an unbroken sequence of nine straight days. Fortunately, despite this being one of the largest extended outbreaks of tornadoes on record, it did not cause as many fatalities as in the few comparable past outbreaks, due in large measure to the warning efforts of National Weather Service, television, and private-company forecasters and the smaller number of violent (F4 F5) tornadoes. This event was also relatively predictable; the onset of the outbreak was forecast skillfully many days in advance.An unusually persistent upper-level trough in the intermountain west and sustained low-level southerly winds through the southern Great Plains produced the extended period of tornado-favorable conditions. Three other extended outbreaks in the past 88 years were statistically comparable to this outbreak, and two short-duration events (Palm Sunday 1965 and the 1974 Superoutbreak) were comparable in the overall number of strong tornadoes. An analysis of tornado statistics and environmental conditions indicates that extended outbreaks of this character occur roughly every 10 to 100 years.


  3. Dust control for Enabler

    NASA Technical Reports Server (NTRS)

    Hilton, Kevin; Karl, Chad; Litherland, Mark; Ritchie, David; Sun, Nancy

    1992-01-01

    The dust control group designed a system to restrict dust that is disturbed by the Enabler during its operation from interfering with astronaut or camera visibility. This design also considers the many different wheel positions made possible through the use of artinuation joints that provide the steering and wheel pitching for the Enabler. The system uses a combination of brushes and fenders to restrict the dust when the vehicle is moving in either direction and in a turn. This design also allows for each of maintenance as well as accessibility of the remainder of the vehicle.

  4. Dust control for Enabler

    NASA Technical Reports Server (NTRS)

    Hilton, Kevin; Karl, Chad; Litherland, Mark; Ritchie, David; Sun, Nancy

    1992-01-01

    The dust control group designed a system to restrict dust that is disturbed by the Enabler during its operation from interfering with astronaut or camera visibility. This design also considers the many different wheel positions made possible through the use of artinuation joints that provide the steering and wheel pitching for the Enabler. The system uses a combination of brushes and fenders to restrict the dust when the vehicle is moving in either direction and in a turn. This design also allows for ease of maintenance as well as accessibility of the remainder of the vehicle.

  5. Dust torus around Mars

    NASA Technical Reports Server (NTRS)

    Juhasz, Antal; Horanyi, Mihaly

    1995-01-01

    We investigate the orbital dynamics of small dust particles generated via the continuous micrometeoroid bombardment of the Martian moons. In addition to Mar's oblateness, we also consider the radiation pressure perturbation that is complicated by the planet's eccentric orbit and tilted rotational axis. Considering the production rates and the lifetimes of dust grains, we show that particles from Deimos with radii of about 15 micrometers are expected to dominate the population of a permanently present and tilted dust torus. This torus has an estimated peak number density of approximately equals 5 x 10(exp -12)/cu cm and an optical depth of approximately equals 4 x 10(exp -8).

  6. Dust in the Mediterranean

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On July 24, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), acquired this true-color image of a large cloud of dust blowing from northern Africa across the Mediterranean Sea. The dust storm has persisted in the region for at least a week. In this image, the brownish dust plume appears to originate about 260 miles (400 km) east of Algiers, Algeria, and is blowing toward the northwest coast of Sardinia, Italy. SeaWiFS flies aboard the OrbView-2 Satellite. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE

  7. Electrostatic dust detector

    DOEpatents

    Skinner, Charles H.

    2006-05-02

    An apparatus for detecting dust in a variety of environments which can include radioactive and other hostile environments both in a vacuum and in a pressurized system. The apparatus consists of a grid coupled to a selected bias voltage. The signal generated when dust impacts and shorts out the grid is electrically filtered, and then analyzed by a signal analyzer which is then sent to a counter. For fine grids a correlation can be developed to relate the number of counts observed to the amount of dust which impacts the grid.

  8. Effects of Multi-Decadal Variation of SST and Dust Radiative Forcing on Rainfall and Dust Transport over West Africa and Northern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kim, K. M.; Lau, W. K. M.; Colarco, P. R.

    2014-12-01

    The effects of multi-decadal variations of sea surface temperature (SST) and dust radiative forcing on the West African monsoon rainfall and circulation, and consequent change in dust emission and transport are examined based on model experiments with the NASA GEOS-5 GCM with prescribed SST. SST patterns representing the 1950s and 1980s are obtained based on Singular Value Decomposition (SVD) between Sahel rainfall and global SST distribution, and prescribed for 7-year simulations for each period. Results show that the subtropical high is strengthened and expanded southwestward associated with colder northern Atlantic Ocean SST in 1980s. As a result, the rain band in the tropical Atlantic Ocean and Sahel moves southward and rainfall is reduced over the Sahel. Stronger surface winds associated with strong surface temperature gradients increase dust emission in the southern Saharan desert and northern Sahel. Combined with circulation changes induced by strengthening the subtropical high and reduced wet deposition, dust transport is increased in the deep tropics (10-20N), but reduced in the northern path (20-30N)To examine the effect of aerosol radiative forcing, additional experiments are conducted after dust radiative feedback is turned off. Without aerosol radiative feedback, model still simulate aforementioned contrast between 1980s and 1950s, but the anomalies of Sahel drought and dust transports are a lot weaker. Preliminary results indicate that atmospheric heating due to shortwave absorption by dust provides additional buoyance and lifts dust particles to higher altitudes. Dust radiative forcing also increases meridional temperature gradients and strengthens the African Easterly Jet, resulting in an increased residence time of dust and farther westward transport.

  9. Global transport of thermophilic bacteria in atmospheric dust.

    PubMed

    Perfumo, Amedea; Marchant, Roger

    2010-04-01

    Aerosols from dust storms generated in the Sahara-Sahel desert area of Africa are transported north over Europe and periodically result in dry dust precipitation in the Mediterranean region. Samples of dust collected in Turkey and Greece following two distinct desert storm events contained viable thermophilic organisms of the genus Geobacillus, namely G. thermoglucosidasius and G. thermodenitrificans, and the recently reclassified Aeribacillus pallidus (formerly Geobacillus pallidus). We present here evidence that African dust storms create an atmospheric bridge between distant geographical regions and that they are also probably the source of thermophilic geobacilli later deposited over northern Europe by rainfall or dust plumes themselves. The same organisms (99% similarity in the 16S rDNA sequence) were found in dust collected in the Mediterranean region and inhabiting cool soils in Northern Ireland. This study also contributes new insights to the taxonomic identification of Geobacillus sp. Attempts to identify these organisms using 16S rRNA gene sequences have revealed that they contain multiple and diverse copies of the ribosomal RNA operon (up to 10 copies with nine different sequences), which dictates care in interpreting data about the systematics of this genus. PMID:23766086

  10. A public health issue related to collateral seismic hazards: The valley fever outbreak triggered by the 1994 Northridge, California earthquake

    USGS Publications Warehouse

    Jibson, R.W.

    2002-01-01

    Following the 17 January 1994 Northridge. California earthquake (M = 6.7), Ventura County, California, experienced a major outbreak of coccidioidomycosis (CM), commonly known as valley fever, a respiratory disease contracted by inhaling airborne fungal spores. In the 8 weeks following the earthquake (24 January through 15 March), 203 outbreak-associated cases were reported, which is about an order of magnitude more than the expected number of cases, and three of these cases were fatal. Simi Valley, in easternmost Ventura County, had the highest attack rate in the county, and the attack rate decreased westward across the county. The temporal and spatial distribution of CM cases indicates that the outbreak resulted from inhalation of spore-contaminated dust generated by earthquake-triggered landslides. Canyons North East of Simi Valley produced many highly disrupted, dust-generating landslides during the earthquake and its aftershocks. Winds after the earthquake were from the North East, which transported dust into Simi Valley and beyond to communities to the West. The three fatalities from the CM epidemic accounted for 4 percent of the total earthquake-related fatalities.

  11. Saharan and Arabian Dust Aerosols: A Comparative Case Study of Lidar Ratio

    NASA Astrophysics Data System (ADS)

    Córdoba-Jabonero, Carmen; Sabbah, Ismail; Sorribas, Mar; Adame, José Antonio; Cuevas, Emilio; Sharifi, Faisal Al; Gil-Ojeda, Manuel

    2016-06-01

    This work presents a first comparative study of the Lidar Ratio (LR) values obtained for dust particles in two singular dust-influenced regions: the Canary Islands (Spain, close to the African coast in the North Atlantic Ocean), frequently affected by Saharan dust intrusions, and the Kuwait area (Arabian Peninsula) as usually influenced by Arabian dust storms. Synergetic lidar and sun-photometry measurements are carried out in two stations located in these particular regions for that purpose. Several dusty cases were observed during 2014 in both stations and, just for illustration, two specific dusty case studies have been selected and analyzed to be shown in this work. In general, mean LR values of 54 sr and 40 sr were obtained in these studies cases for Saharan and Arabian dust particles, respectively. Indeed, these results are in agreement with other studies performed for dust particles arriving from similar desert areas. In particular, the disparity found in Saharan and Arabian dust LR values can be based on the singular composition of the suspended dust aerosols over each station. These results can be useful for CALIPSO extinction retrievals, where a single LR value (40 sr) is assumed for pure dust particles independently on the dust source region.

  12. The African Connection

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2012-01-01

    From student and faculty exchanges to joint research projects, U.S. universities maintain a broad spectrum of collaborative relationships with African universities. It's unclear how many U.S. colleges and universities have partnerships with African universities. The African Studies Association, an organization of scholars, doesn't keep that kind…

  13. A Hospital-wide Outbreak of Serratia marcescens, and Ishikawa's "Fishbone" Analysis to Support Outbreak Control.

    PubMed

    Vetter, Luzia; Schuepfer, Guido; Kuster, Stefan P; Rossi, Marco

    2016-01-01

    A nosocomial outbreak of Serratia marcescens in respiratory samples predominantly from patients in a surgical intensive care unit is reported. Most of these patients were cardiac surgical patients. Initially, a vigorous but inconclusive investigation was implemented on the basis of standardized (according the US Centers for Disease Control and Prevention) steps of outbreak investigation. Then, a systemic quality management approach with "fishbone" analysis was added. As a consequence, plausible causes for the outbreak were identified: (i) S marcescens was found on the transesophageal echocardiography probe used during cardiac surgery; and (ii) the quality of the surface disinfection was insufficient due to multiple reasons and was completely reengineered. In conclusion, in addition to the standardized steps of outbreak investigation, the complementary use of quality management tools such as the Ishikawa "fishbone" analysis is helpful for outbreak control. The complete reengineering of the disinfectant procurement and logistics is assumed to have been the most effective measure to control the described outbreak. PMID:26783861

  14. Dust mite (image)

    MedlinePlus

    This is a magnified photograph of a dust mite. Mites are carriers (vectors) of many important diseases including typhus (scrub and murine) and rickettsialpox. (Image courtesy of the Centers for Disease ...

  15. Dusts and Molds

    MedlinePlus

    ... of dust can result in sensitization. Symptoms include chills, fever, cough, chest congestion, fatigue, and shortness of ... grain and forage products. Symptoms include cough, fever, chills, body aches, and fatigue. These symptoms appear from ...

  16. 1983 Transatlantic Dust Event

    NASA Video Gallery

    This visualization (prepared in 2001) shows dust being blown westward over the Atlantic from northern Africa in early 1983, from aerosol measurements taken by Nimbus 7's TOMS instrument. Saharan du...

  17. Adhesion of Lunar Dust

    NASA Astrophysics Data System (ADS)

    Walton, Otis R.

    2007-04-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  18. The Lunar Dust Pendulum

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Stubbs, Timothy J.; Farrell, William M.

    2011-01-01

    Shadowed regions on the lunar surface acquire a negative potential. In particular, shadowed craters can have a negative potential with respect to the surrounding lunar regolith in sunlight, especially near the terminator regions. Here we analyze the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum. Previous models describing the transport of charged lunar dust close to the surface have typically been limited to one-dimensional motion in the vertical direction, e.g. electrostatic levitation; however, the electric fields in the vicinity of shadowed craters will also have significant components in the horizontal directions. We propose a model that includes both the horizontal and vertical motion of charged dust grains near shadowed craters. We show that the dust grains execute oscillatory trajectories and present an expression for the period of oscillation drawing an analogy to the motion of a pendulum.

  19. The Lunar Dust Pendulum

    NASA Technical Reports Server (NTRS)

    Kuntz, Kip; Collier, Michael R.; Stubbs, Timothy J.; Farrell, William M.

    2011-01-01

    Shadowed regions on the lunar surface acquire a negative potential. In particular, shadowed craters can have a negative potential with respect to the surrounding lunar regolith in sunlight, especially near the terminator regions. Here we analyze the motion of a positively charged lnnar dust grain in the presence of a shadowed crater at a negative potential in vacuum. Previous models describing the transport of charged lunar dust close to the surface have typically been limited to one-dimensional motion in the vertical direction, e.g. electrostatic levitation; however. the electric fields in the vicinity of shadowed craters will also have significant components in the horizontal directions. We propose a model that includes both the horizontal and vertical motion of charged dust grains near shadowed craters. We show that the dust grains execute oscillatory trajectories and present an expression for the period of oscillation drawing an analogy to the motion of a pendulum.

  20. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  1. Dust and Smoke

    Atmospheric Science Data Center

    2014-05-15

    ... dust, the most common non-spherical aerosol type, from pollution and forest fire particles. Determining aerosol characteristics is a ... higher, indicating the relative abundance of small pollution particles, especially over the Atlantic where the aerosol optical ...

  2. Hospitalization and Antimicrobial Resistance in Salmonella Outbreaks, 1984–2002

    PubMed Central

    Greene, Katherine D.; Ovitt, Jessa; Barrett, Timothy J.; Medalla, Felicita; Angulo, Frederick J.

    2005-01-01

    Few studies have evaluated the health consequences of antimicrobial-resistant Salmonella strains associated with outbreaks. Among 32 outbreaks occurring in the United States from 1984 to 2002, 22% of 13,286 persons in 10 Salmonella-resistant outbreaks were hospitalized, compared with 8% of 2,194 persons in 22 outbreaks caused by pansusceptible Salmonella strains (p<0.01). PMID:15963293

  3. Waterborne outbreak of tularemia associated with crayfish fishing.

    PubMed Central

    Anda, P.; Segura del Pozo, J.; Díaz García, J. M.; Escudero, R.; García Peña, F. J.; López Velasco, M. C.; Sellek, R. E.; Jiménez Chillarón, M. R.; Sánchez Serrano, L. P.; Martínez Navarro, J. F.

    2001-01-01

    In 1997, an outbreak of human tularemia associated with hare-hunting in central Spain affected 585 patients. We describe the identification of Francisella tularensis biovar palaearctica in a second outbreak of ulceroglandular tularemia associated with crayfish (Procambarus clarkii) fishing in a contaminated freshwater stream distant from the hare-associated outbreak. The second outbreak occurred 1 year after the first. PMID:11485678

  4. Dengue: Lessons of an Outbreak

    PubMed Central

    Siddiqui, Oves; Abhishek, Kumar S.

    2016-01-01

    Introduction Since 1967 there have been many outbreaks of dengue in Delhi. In the year 2015 Delhi has suffered it’s one of the worst dengue outbreaks, with more than 15000 dengue confirmed cases and the highest number of deaths (60) in recent years. Aim To determine the status of Dengue cases as compared to previous six years, the ratio of primary and secondary dengue cases and to review the effectiveness of the one test strategy (either NS1 antigen or IgM antibody) for the confirmation of Dengue. Materials and Methods A cross-sectional study was performed in the year 2015. A total of 7177 serum samples were tested for the confirmation of suspected cases of dengue at our institute. We performed dengue NS1 antigen and dengue IgM antibody ELISA tests for the confirmation of dengue cases in acute and convalescent fever cases respectively. Hundred random samples negative for NS1 antigen were tested for IgM antibody and 100 random samples negative for IgM antibody were tested for NS1 antigen. For determination of ratio of primary and secondary dengue cases, IgG Avidity ELISA was performed on random 76 dengue positive samples. Results Out of 7177 samples tested, 2358 were positive either by NS1 antigen or for IgM antibody from January to December. Percentage positivity rates for IgM antibody detection and NS1 antigen detection tests were 24.8% (626) and 37.1% (1732) respectively. Out of 100 NS1 negative samples 8 were positive for IgM antibody and out of 100 IgM negative samples 6 were positive for NS1 antigen. Among the 76 samples tested for dengue IgG Avidity ELISA 52 (68.4%) were found to be of secondary dengue. Conclusion Number of dengue cases is constantly rising in Delhi since 2011 and 2014. IgM antibody detection and NS1 antigen detection both the tests should be performed for each patient. Due to the increased prevalence of past infection of dengue, percentage of secondary dengue cases is also increasing in Delhi.

  5. The Galileo dust detector

    NASA Technical Reports Server (NTRS)

    Gruen, E.; Fechtig, H.; Hanner, M. S.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Maas, D.; Morfill, G. E.; Zook, H. A.

    1990-01-01

    The Galileo Dust Detector is intended to provide direct observations of dust grains with masses between 10(sup -19) kg and 10(sup -9) kg in interplanetary space and in the Jovian system, to investigate their physical and dynamical properties as functions of the distances to the Sun, to Jupiter and to its satellites, to study its interaction with the Galilean satellites and the Jovian magnetosphere. Surface phenomena of the satellites (like albedo variations), which might be effects of meteoroid impacts will be compared with the dust environment. Electric charges of particulate matter in the magnetosphere and its consequences will be studied; e.g. the effects of the magnetic field on the trajectories of dust particles and fragmentation of particles due to electrostatic disruption. The investigation is performed with an instrument that measures the mass, speed, flight direction and electric charge of individual dust particles. It is a multi-coincidence detector with a mass sensitivity 10(sup 6) times higher than that of previous in-situ experiments which measured dust in the outer solar system. The instrument weighs 4.2 kg, consumes 2.4 W, and has a normal data transmission rate of 24 bits/s in nominal spacecraft tracking mode. On December 29, 1989 the instrument was switched-on. After the instrument had been configured to flight conditions cruise science data collection started immediately. In the period to May 18, 1990 at least 168 dust impacts have been recorded. For 81 of these dust grains, masses and impact speeds have been determined. First flux values are also given.

  6. Dust storm detection using random forests and physical-based approaches over the Middle East

    NASA Astrophysics Data System (ADS)

    Souri, Amir Hossein; Vajedian, Sanaz

    2015-07-01

    Dust storms are important phenomena over large regions of the arid and semi-arid areas of the Middle East. Due to the influences of dust aerosols on climate and human daily activities, dust detection plays a crucial role in environmental and climatic studies. Detection of dust storms is critical to accurately understand dust, their properties and distribution. Currently, remotely sensed data such as MODIS (Moderate Resolution Imaging Spectroradiometer) with appropriate temporal and spectral resolutions have been widely used for this purpose. This paper investigates the capability of two physical-based methods, and random forests (RF) classifier, for the first time, to detect dust storms using MODIS imagery. Since the physical-based approaches are empirical, they suffer from certain drawbacks such as high variability of thresholds depending on the underlying surface. Therefore, classification-based approaches could be deployed as an alternative. In this paper, the most relevant bands are chosen based on the physical effects of the major classes, particularly dust, cloud and snow, on both emissive infrared and reflective bands. In order to verify the capability of the methods, OMAERUV AAOD (aerosol absorption optical depth) product from OMI (Ozone Monitoring Instrument) sensor is exploited. In addition, some small regions are selected manually to be considered as ground truth for measuring the probability of false detection (POFD) and probability of missing detection (POMD). The dust class generated by RF is consistent qualitatively with the location and extent of dust observed in OMERAUV and MODIS true colour images. Quantitatively, the dust classes generated for eight dust outbreaks in the Middle East are found to be accurate from 7% and 6% of POFD and POMD respectively. Moreover, results demonstrate the sound capability of RF in classifying dust plumes over both water and land simultaneously. The performance of the physical-based approaches is found weaker than RF

  7. Hebes Chasma Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Dust avalanches, also called slope streaks, occur on many Martian terrains. The deposition of airborne dust on surfaces causes a bright tone in the THEMIS VIS images. Any movement of the dust downhill, a dust avalanche, will leave behind a streak where the darker, dust-free surface is exposed.

    These dust avalanches are located in Hebes Chasma.

    Image information: VIS instrument. Latitude -1.4, Longitude 286.6 East (73.4 West). 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Comments on Dust Reverberation

    NASA Astrophysics Data System (ADS)

    Peterson, B.

    2015-09-01

    Dust reverberation is an important technique for studying the inner structure of AGNs and probing the properties of astrophysical dust, and even has some potential as a cosmological probe. We will discuss two recent results that pose a serious limitation to understanding dust reverberation at the present time. First, recent high-cadence monitoring of the UV and optical continuum in two AGNs, NGC 2617 and NGC 5548, have yielded unambiguous lags between variations of the UV continuum and corresponding variations of the continuum at longer wavelengths. In the absence of UV data, this leads to a systematic underestimate of the innermost radius where dust is found. This similarly leads to an underestimate of the size of the broad emission-line region, although it does not affect the AGN black hole mass scale, which calibrates out this effect. Second, broad-band monitoring of continuum variations in the optical through near-IR show that the innermost dust is not necessarily at the 'instantaneous sublimation radius.' The innermost dust can be considerably cooler than expected at the sublimation radius and thus can heat up without sublimating when the central continuum source becomes more luminous (see the poster by Pott).

  9. Argyre Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-363, 17 May 2003

    This summertime Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) view of the floor of Argyre Basin shows a plethora of dark streaks thought to have been created by the passage of dust devils. Dust devils are vortices of wind--just as a tornado is a vortex of wind associated with stormy weather on Earth, and the spiraling of water down a bathtub drain is a vortex in a liquid. Dust devils usually form on Mars on relatively calm, quiet, spring and summer afternoons. The passage of a dust devil picks up and disturbs the thin coatings of dust on the martian surface, forming streaks that mark the path that the moving dust devil took. This picture covers an area 3 km (1.9 mi) wide and is located near 48.5oS, 43.0oW. Sunlight illuminates the scene from the upper left.

  10. Ares Vallis Dust Devil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    12 May 2004 When it was operating in the Ares/Tiu Valles region of Chryse Planitia, Mars, in 1997, Mars Pathfinder detected dust devils that passed over and near the lander. From orbit, no images of dust devils at the Mars Pathfinder site have yet been acquired, but this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime dust devil near the rim of a 610-meter (670 yards)-diameter impact crater in the same general region as the Mars Pathfinder site. This scene is near 19.6oN, 32.9oW, in part of the Ares Vallis system. The dust devil in this case is not making a streak, as dust devils tend to do in some regions of Mars. The dark feature to the right (east) of the dust devil is its shadow. This picture covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left/upper left.

  11. Selecting baghouse dust collectors

    SciTech Connect

    Moore, S.; Rubak, J.; Jolin, M. |

    1996-10-01

    Control of nuisance or process dusts generated within a plant is a vital concern with today`s growing emphasis on indoor air quality. In the past, many companies simply moved these contaminants away from workers and discharged them into the atmosphere. More stringent pollution control requirements now make this course of action unacceptable. Also, in some cases there is a need to recover high-value dusts, such as chemicals or precious metals. As a result, proper design and selection of a dust collection system are more critical than ever. There are two types of fabric filter dust collection systems commonly used today: baghouses and cartridges. Baghouses were the first collection systems with fabric media (in the form of long tubes, or bags) for removal of contaminants. The versatility of the baghouse--coupled with constant technological refinements--have made it a long-standing favorite among specifiers of pollution control equipment. In fact, baghouses account for more than 80% of all fabric filter dust collection systems in use today. Cartridge dust collectors use rigidly pleated filter elements instead of bags, making it possible to accommodate a large amount of filter surface area in a comparatively small package. Cartridge collectors also offer high efficiency and low pressure drop.

  12. Infection Control During Filoviral Hemorrhagic Fever Outbreaks

    PubMed Central

    Vanessa, N Raabe; Matthias, Borchert

    2012-01-01

    Breaking the human-to-human transmission cycle remains the cornerstone of infection control during filoviral (Ebola and Marburg) hemorrhagic fever outbreaks. This requires effective identification and isolation of cases, timely contact tracing and monitoring, proper usage of barrier personal protection gear by health workers, and safely conducted burials. Solely implementing these measures is insufficient for infection control; control efforts must be culturally sensitive and conducted in a transparent manner to promote the necessary trust between the community and infection control team in order to succeed. This article provides a review of the literature on infection control during filoviral hemorrhagic fever outbreaks focusing on outbreaks in a developing setting and lessons learned from previous outbreaks. The primary search database used to review the literature was PUBMED, the National Library of Medicine website. PMID:22529631

  13. Outbreak of Nosocomial Listeriosis — Texas, 2010

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Invasive listeriosis is a potentially fatal foodborne disease caused by Listeria monocytogenes. In February 2010, a listeriosis cluster was identified in Texas. We investigated to confirm the outbreak, identify the source, and prevent additional infections. Methods: All clinical isol...

  14. An outbreak of rubella among hospital personnel.

    PubMed

    Polk, B F; White, J A; DeGirolami, P C; Modlin, J F

    1980-09-01

    An outbreak of 47 cases of rubella occurred among hospital personnel in a large medical-surgical hospital. As a result, one pregnancy was terminated and 475 employee workdays were lost. Epidemiologic investigation of the outbreak suggested a common source; a dietary worker was identified as the probable index case. Serum samples of 12 per cent of women employees were negative for rubella antibody at the time of the outbreak. Neither a history of rubella nor a history of immunization with rubella vaccine was reliable in the prediction of the presence or absence of immunity. Two thirds of all hospital personnel were immunized through a voluntary mass-immunization program, but the response of physicians to the program was disappointing. Outbreaks of rubella that occur in hospitals with prenatal clinics are of special concern. Testing of all employees for rubella antibody and immunization of those determined to be seronegative should be considered. PMID:7402219

  15. Norovirus: U.S. Trends and Outbreaks

    MedlinePlus

    ... Norovirus outbreaks can also occur from fecal (stool) contamination of certain foods at their source. For example, ... may also result from infected crew or environmental contamination. This is because norovirus can persist on surfaces ...

  16. Characterization of the dengue outbreak in Nuevo Leon state, Mexico, 2010.

    PubMed

    Leduc-Galindo, D; Gloria-Herrera, U; Rincón-Herrera, U; Ramos-Jiménez, J; Garcia-Luna, S; Arellanos-Soto, D; Mendoza-Tavera, N; Tavitas-Aguilar, I; Garcia-Garcia, E; Galindo-Galindo, E; Villarreal-Perez, J; Fernandez-Salas, I; Santiago, G A; Muñoz-Jordan, J; Rivas-Estilla, A M

    2015-04-01

    We studied serotypes circulating dengue virus (DENV) cases, entomological Breteau index, rain-fall index and epidemiology of groups affected during the 2010 outbreak in Nuevo Leon, Mexico. From 2,271 positive cases, 94% were dengue classic and 6% dengue hemorrhagic fever; DENV1 was mainly isolated (99%) (Central-American lineage of American-African-genotype). We found correlation between two environmental phenomena (Increment of rainfall and vector-indexes) (p ≤ 0.05) with epidemiological, clinical and risk of DENV-1 ongoing transmission. PMID:25573274

  17. Newton to Einstein — dust to dust

    SciTech Connect

    Kopp, Michael; Uhlemann, Cora; Haugg, Thomas E-mail: cora.uhlemann@physik.lmu.de

    2014-03-01

    We investigate the relation between the standard Newtonian equations for a pressureless fluid (dust) and the Einstein equations in a double expansion in small scales and small metric perturbations. We find that parts of the Einstein equations can be rewritten as a closed system of two coupled differential equations for the scalar and transverse vector metric perturbations in Poisson gauge. It is then shown that this system is equivalent to the Newtonian system of continuity and Euler equations. Brustein and Riotto (2011) conjectured the equivalence of these systems in the special case where vector perturbations were neglected. We show that this approach does not lead to the Euler equation but to a physically different one with large deviations already in the 1-loop power spectrum. We show that it is also possible to consistently set to zero the vector perturbations which strongly constrains the allowed initial conditions, in particular excluding Gaussian ones such that inclusion of vector perturbations is inevitable in the cosmological context. In addition we derive nonlinear equations for the gravitational slip and tensor perturbations, thereby extending Newtonian gravity of a dust fluid to account for nonlinear light propagation effects and dust-induced gravitational waves.

  18. Outbreaks of Hantavirus induced by seasonality

    NASA Astrophysics Data System (ADS)

    Buceta, J.; Escudero, C.; de La Rubia, F. J.; Lindenberg, Katja

    2004-02-01

    Using a model for rodent population dynamics, we study outbreaks of Hantavirus infection induced by the alternation of seasons. Neither season by itself satisfies the environmental requirements for propagation of the disease. This result can be explained in terms of the seasonal interruption of the relaxation process of the mouse population toward equilibrium, and may shed light on the reported connection between climate variations and outbreaks of the disease.

  19. Meningococcal meningitis outbreak control strategies.

    PubMed

    Ahlawat, S; Kumar, R; Roy, P; Varma, S; Sharma, B K

    2000-12-01

    Meningococcal meningitis has been occurring worldwide in both endemic and epidemic forms. Serogroup A accounts for majority of cases of epidemic as well as endemic Meningococcal meningitis in developing nations, whereas group C and group B causes epidemic and endemic meningococcal meningitis in developed countries. Person to person spread of N. meningitides generally occurs through inhalation of droplets of infected nasopharyngeal secretions by direct or indirect oral contact. Incubation period varies from 2 to 10 days. N. meningitides typically causes acute infective illness characterized by sequential development of upper respiratory tract infection, meningococcemia, meningitis and focal neurological deficit. Over 90 per cent cases of adult meningococcal infections have cerebrospinal meningitis, whereas in children prevalence of meningitis is much lower (50 per cent). Acute meningitis manifests with fever, severe headache, vomiting and neck stiffness. Presentations may be non-specific in infants, elderly and in patients with fulminant meningococcemia. Diagnosis is confirmed with cerebrospinal fluid analysis. Overall mortality due to meningitis is usually around 10 per cent. In meningococcal septicemia, the case fatality rate may exceed 50 per cent. Preventive strategies include vaccination, chemoprophylaxis and early detection and treatment. Mass vaccination campaign, if appropriately carried out, has been documented to halt an epidemic of meningococcal disease due to serogroup A or C. In the present review we have discussed the available evidence with regards to prevention at primary, secondary and tertiary level. Public health approach to an outbreak of meningococcal meningitis in a community or an organization is also outlined. PMID:11668937

  20. Investigation of multistate foodborne disease outbreaks.

    PubMed

    Sobel, Jeremy; Griffin, Patricia M; Slutsker, Laurence; Swerdlow, David L; Tauxe, Robert V

    2002-01-01

    The U.S. food supply is characterized increasingly by centralized production and wide distribution of products, and more foodborne disease outbreaks are dispersed over broad geographic areas. Such outbreaks may present as a gradual, diffuse, and initially unapparent increase in sporadic cases. Recognition and reporting by clinicians and local public health officials and the ordering of laboratory tests by clinicians continue to be cornerstones of detecting all outbreaks. New methods--such as active laboratory-based surveillance, automated algorithms for detecting increases in infection rates, and molecular subtyping--facilitate detection of diffuse outbreaks. Routines have evolved for the investigation of multistate outbreaks; they are characterized by rapid communication between local, state, and federal public health officials; timely review of epidemiologic data by expert panels; collaboration on tracebacks with food safety regulatory agencies; and communication with the public and media. Rapid, efficient investigation of multistate outbreaks may result in control of acute public health emergencies, identification and correction of hazardous food production and processing practices, and consequent improvement in food safety. PMID:12297677

  1. Understanding the impact of saharan dust aerosols on tropical cyclones

    NASA Astrophysics Data System (ADS)

    Naeger, Aaron

    Genesis of Tropical Cyclones (TCs) in the main development region for Atlantic hurricanes is tied to convection initiated by African easterly waves (AEWs) during Northern hemisphere summer and fall seasons. The main development region is also impacted by dust aerosols transported from the Sahara. It has been hypothesized that dust aerosols can modulate the development of TCs through aerosol-radiation and aerosol-cloud interaction processes. In this study, we investigate the impact of dust aerosols on TC development using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem). We first develop a technique to constrain the WRF-Chem model with a realistic three-dimensional spatial distribution of dust aerosols. The horizontal distribution of dust is specified using the Moderate Resolution Imaging Spectroradiometer (MODIS) derived aerosol products and output from the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. The vertical distribution of dust is constrained using the Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). We validate our technique through in situ aircraft measurements where both showed aerosol number concentrations from 20-30 cm-3 in the atmosphere for Saharan dust moving over the eastern Atlantic Ocean. Then, we use the satellite data constraint technique to nudge the WRF-Chem aerosol fields throughout the simulation of TC Florence developing over the eastern Atlantic Ocean during September 2006. Three different experiments are conducted where the aerosol-radiation and aerosol-cloud interaction processes are either activated or deactivated in the model while all other model options are identical between the experiments. By comparing the model experiment results, the impact of the aerosol interaction processes on TC development can be understood. The results indicate that dust aerosols can delay or prevent the development of a TC as the minimum sea level pressure of TC Florence was 13 h

  2. Interstellar and Cometary Dust

    NASA Technical Reports Server (NTRS)

    Mathis, John S.

    1997-01-01

    'Interstellar dust' forms a continuum of materials with differing properties which I divide into three classes on the basis of observations: (a) diffuse dust, in the low-density interstellar medium; (b) outer-cloud dust, observed in stars close enough to the outer edges of molecular clouds to be observed in the optical and ultraviolet regions of the spectrum, and (c) inner-cloud dust, deep within the cores of molecular clouds, and observed only in the infrared by means of absorption bands of C-H, C=O, 0-H, C(triple bond)N, etc. There is a surprising regularity of the extinction laws between diffuse- and outer-cloud dust. The entire mean extinction law from infrared through the observable ultraviolet spectrum can be characterized by a single parameter. There are real deviations from this mean law, larger than observational uncertainties, but they are much smaller than differences of the mean laws in diffuse- and outer-cloud dust. This fact shows that there are processes which operate over the entire distribution of grain sizes, and which change size distributions extremely efficiently. There is no evidence for mantles on grains in local diffuse and outer-cloud dust. The only published spectra of the star VI Cyg 12, the best candidate for showing mantles, does not show the 3.4 micro-m band which appreciable mantles would produce. Grains are larger in outer-cloud dust than diffuse dust because of coagulation, not accretion of extensive mantles. Core-mantle grains favored by J. M. Greenberg and collaborators, and composite grains of Mathis and Whiffen (1989), are discussed more extensively (naturally, I prefer the latter). The composite grains are fluffy and consist of silicates, amorphous carbon, and some graphite in the same grain. Grains deep within molecular clouds but before any processing within the solar system are presumably formed from the accretion of icy mantles on and within the coagulated outer-cloud grains. They should contain a mineral

  3. Changes in Stratiform Clouds of Mesoscale Convective Complex Introduced by Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Lin, B.; Min, Q.-L.; Li, R.

    2010-01-01

    Aerosols influence the earth s climate through direct, indirect, and semi-direct effects. There are large uncertainties in quantifying these effects due to limited measurements and observations of aerosol-cloud-precipitation interactions. As a major terrestrial source of atmospheric aerosols, dusts may serve as a significant climate forcing for the changing climate because of its effect on solar and thermal radiation as well as on clouds and precipitation processes. Latest satellites measurements enable us to determine dust aerosol loadings and cloud distributions and can potentially be used to reduce the uncertainties in the estimations of aerosol effects on climate. This study uses sensors on various satellites to investigate the impact of mineral dust on cloud microphysical and precipitation processes in mesoscale convective complex (MCC). A trans-Atlantic dust outbreak of Saharan origin occurring in early March 2004 is considered. For the observed MCCs under a given convective strength, small hydrometeors were found more prevalent in the dusty stratiform regions than in those regions that were dust free. Evidence of abundant cloud ice particles in the dust regions, particularly at altitudes where heterogeneous nucleation of mineral dust prevails, further supports the observed changes of clouds and precipitation. The consequences of the microphysical effects of the dust aerosols were to shift the size spectrum of precipitation-sized hydrometeors from heavy precipitation to light precipitation and ultimately to suppress precipitation and increase the lifecycle of cloud systems, especially over stratiform areas.

  4. Characteristics of extreme dust events observed over two urban areas in Iran

    NASA Astrophysics Data System (ADS)

    Bidokhti, Abbas-Ali A.; Gharaylou, Maryam; Pegahfar, Nafiseh; Sabetghadam, Samaneh; Rezazadeh, Maryam

    2016-03-01

    Determination of dust loading in the atmosphere is important not only from the public health point of view, but also for regional climate changes. The present study focuses on the characteristics of two major dust events for two urban areas in Iran, Kermanshah and Tehran, over the period of 4 years from 2006 to 2009. To detect extreme dust outbreaks, various datasets including synoptic data, dust concentration, reanalysis data and numerical results of WRF and HYSPLIT models were used. The weather maps demonstrate that for these events dusts are mainly generated when wind velocity is high and humidity is low in the lower troposphere and the region is under the influence of a thermal low. The event lasts until the atmospheric stability prevails and the surface wind speed weakens. The thermal low nature of the synoptic conditions of these major events is also responsible for deep boundary layer development with its thermals affecting the vertical dust flux over the region. Trajectory studies show that the dust events originated from deserts in Iraq and Syria and transported towards Iran. The main distinction between the two types of mobilizations seems to affect the dust concentrations in the Tehran urban area.

  5. Use of Combined A-Train Observations to Validate GEOS Model Simulated Dust Distributions During NAMMA

    NASA Technical Reports Server (NTRS)

    Nowottnick, E.

    2007-01-01

    During August 2006, the NASA African Multidisciplinary Analyses Mission (NAMMA) field experiment was conducted to characterize the structure of African Easterly Waves and their evolution into tropical storms. Mineral dust aerosols affect tropical storm development, although their exact role remains to be understood. To better understand the role of dust on tropical cyclogenesis, we have implemented a dust source, transport, and optical model in the NASA Goddard Earth Observing System (GEOS) atmospheric general circulation model and data assimilation system. Our dust source scheme is more physically based scheme than previous incarnations of the model, and we introduce improved dust optical and microphysical processes through inclusion of a detailed microphysical scheme. Here we use A-Train observations from MODIS, OMI, and CALIPSO with NAMMA DC-8 flight data to evaluate the simulated dust distributions and microphysical properties. Our goal is to synthesize the multi-spectral observations from the A-Train sensors to arrive at a consistent set of optical properties for the dust aerosols suitable for direct forcing calculations.

  6. Phylogenetic Analysis of Rubella Virus Strains from an Outbreak in Madrid, Spain, from 2004 to 2005 ▿ †

    PubMed Central

    Martínez-Torres, A. O.; Mosquera, M. M.; Sanz, J. C.; Ramos, B.; Echevarría, J. E.

    2009-01-01

    An outbreak of rubella affected 460 individuals in 2004 and 2005 in the community of Madrid, Spain. Most of the patients were nonvaccinated Latin American immigrants or Spanish males. This study presents the first data on rubella virus genotypes in Spain. Forty selected clinical samples (2 urine, 5 serum, 3 blood, 2 saliva, and 28 pharyngeal exudate samples) from 40 cases were collected. The 739-nucleotide sequence recommended by the World Health Organization obtained from viral RNA in these samples was analyzed by using the MEGA v4.0 software. Seventeen isolates were obtained from 40 clinical samples from the outbreak, including two isolated from congenital rubella syndrome cases. Only viral RNA of genotype 1j was detected in both isolates and clinical specimens. Two variations in amino acids, G253C and T394S, which are involved in neutralization epitopes arose during the outbreak, but apparently there was no positive selection of either of them. The origin of the outbreak remains unknown because of poor virologic surveillance in Latin America and the African countries neighboring Spain. On the other hand, this is the first report of this genotype in Europe. The few published sequences of genotype 1j indicate that it comes from Japan and the Philippines, but there are no epidemiological data supporting this as the origin of the Madrid outbreak. PMID:19020066

  7. Fractal dust grains in plasma

    SciTech Connect

    Huang, F.; Peng, R. D.; Liu, Y. H.; Chen, Z. Y.; Ye, M. F.; Wang, L.

    2012-09-15

    Fractal dust grains of different shapes are observed in a radially confined magnetized radio frequency plasma. The fractal dimensions of the dust structures in two-dimensional (2D) horizontal dust layers are calculated, and their evolution in the dust growth process is investigated. It is found that as the dust grains grow the fractal dimension of the dust structure decreases. In addition, the fractal dimension of the center region is larger than that of the entire region in the 2D dust layer. In the initial growth stage, the small dust particulates at a high number density in a 2D layer tend to fill space as a normal surface with fractal dimension D = 2. The mechanism of the formation of fractal dust grains is discussed.

  8. Salmonellosis outbreak due to Salmonella enteritidis phage type 14b resistant to nalidixic acid, Austria, September 2010.

    PubMed

    Hrivniaková, L; Schmid, D; Luckner-Hornischer, A; Lassnig, H; Kornschober, C; Angermayer, J; Allerberger, F

    2011-01-01

    We report on a salmonellosis-outbreak due to Salmonella Enteritidis phage type 14b resistant to nalidixic acid (S. Enteritidis PT14b Nx) among residents and employees of a student residence in Austria, September 2010. The outbreak was described and analysed by a retrospective cohort study, and microbiological environmental investigations were conducted to identify the outbreak source(s) and the reservoir of the outbreak strain. A total of 66 persons fulfilled the outbreak case definition including 14 laboratory-confirmed cases. Food specific cohort-analyses by day revealed that consumption of potato salad (RR: 1.65, 95%CI: 1.35–2.01, p=0.001) and a cheese-sausage cold plate (RR: 2.24, 95%CI: 1.29–3.88, p=0.002) on 14 September was associated with being an outbreak case. We hypothesised that cross-contamination with S. Enteritidis PT14b Nx positive eggs had occurred during preparation of the potato salad and cold plate as a result of preparing in parallel egg-containing breaded cutlets on 14 September. A traced laying hen holding in eastern Austria was identified as the sole source of the consumable eggs in the student residence. By applying the legally mandated sampling method for epidemiological-related laying hen farms (one pooled dust sample à 150g, two paired boot swabs cultured separately), the outbreak strain could not be detected. Our findings, that legally required sampling methods for laying hen farms failed to detect the causative pathogen in a laying hen holding, despite an epidemiological link, underline the request stated by the European Food Safety Authority Panel on Biological Hazards for a more sensitive sampling plan in epidemiologically-associated laying hen flocks. PMID:21903036

  9. Dust measurements in tokamaks (invited)

    SciTech Connect

    Rudakov, D. L.; Yu, J. H.; Boedo, J. A.; Hollmann, E. M.; Krasheninnikov, S. I.; Moyer, R. A.; Muller, S. H.; Pigarov, A. Yu.; Rosenberg, M.; Smirnov, R. D.; West, W. P.; Boivin, R. L.; Bray, B. D.; Brooks, N. H.; Hyatt, A. W.; Wong, C. P. C.; Roquemore, A. L.; Skinner, C. H.; Solomon, W. M.; Ratynskaia, S.

    2008-10-15

    Dust production and accumulation present potential safety and operational issues for the ITER. Dust diagnostics can be divided into two groups: diagnostics of dust on surfaces and diagnostics of dust in plasma. Diagnostics from both groups are employed in contemporary tokamaks; new diagnostics suitable for ITER are also being developed and tested. Dust accumulation in ITER is likely to occur in hidden areas, e.g., between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In the DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering is able to resolve particles between 0.16 and 1.6 {mu}m in diameter; using these data the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in two-dimension with a single camera or three-dimension using multiple cameras, but determination of particle size is challenging. In order to calibrate diagnostics and benchmark dust dynamics modeling, precharacterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase in carbon line (CI, CII, C{sub 2} dimer) and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  10. Determining inert content in coal dust/rock dust mixture

    DOEpatents

    Sapko, Michael J.; Ward, Jr., Jack A.

    1989-01-01

    A method and apparatus for determining the inert content of a coal dust and rock dust mixture uses a transparent window pressed against the mixture. An infrared light beam is directed through the window such that a portion of the infrared light beam is reflected from the mixture. The concentration of the reflected light is detected and a signal indicative of the reflected light is generated. A normalized value for the generated signal is determined according to the relationship .phi.=(log i.sub.c `log i.sub.co) / (log i.sub.c100 -log i.sub.co) where i.sub.co =measured signal at 0% rock dust i.sub.c100 =measured signal at 100% rock dust i.sub.c =measured signal of the mixture. This normalized value is then correlated to a predetermined relationship of .phi. to rock dust percentage to determine the rock dust content of the mixture. The rock dust content is displayed where the percentage is between 30 and 100%, and an indication of out-of-range is displayed where the rock dust percent is less than 30%. Preferably, the rock dust percentage (RD%) is calculated from the predetermined relationship RD%=100+30 log .phi.. where the dust mixture initially includes moisture, the dust mixture is dried before measuring by use of 8 to 12 mesh molecular-sieves which are shaken with the dust mixture and subsequently screened from the dust mixture.

  11. Electrodynamic Dust Shield Demonstrator

    NASA Technical Reports Server (NTRS)

    Stankie, Charles G.

    2013-01-01

    The objective of the project was to design and manufacture a device to demonstrate a new technology developed by NASA's Electrostatics and Surface Physics Laboratory. The technology itself is a system which uses magnetic principles to remove regolith dust from its surface. This project was to create an enclosure that will be used to demonstrate the effectiveness of the invention to The Office of the Chief Technologist. ONE of the most important challenges of space exploration is actually caused by something very small and seemingly insignificant. Dust in space, most notably on the moon and Mars, has caused many unforeseen issues. Dirt and dust on Earth, while a nuisance, can be easily cleaned and kept at bay. However, there is considerably less weathering and erosion in space. As a result, the microscopic particles are extremely rough and abrasive. They are also electrostatically charged, so they cling to everything they make contact with. This was first noted to be a major problem during the Apollo missions. Dust would stick to the spacesuits, and could not be wiped off as predicted. Dust was brought back into the spacecraft, and was even inhaled by astronauts. This is a major health hazard. Atmospheric storms and other events can also cause dust to coat surfaces of spacecraft. This can cause abrasive damage to the craft. The coating can also reduce the effectiveness of thermal insulation and solar panels.' A group of engineers at Kennedy Space Center's Electrostatics and Surface Physics Laboratory have developed a new technology, called the Electrodynamic Dust Shield, to help alleviate these problems. It is based off of the electric curtain concept developed at NASA in 1967. "The EDS is an active dust mitigation technology that uses traveling electric fields to transport electrostatically charged dust particles along surfaces. To generate the traveling electric fields, the EDS consists of a multilayer dielectric coating with an embedded thin electrode grid

  12. Dust cluster explosion

    SciTech Connect

    Saxena, Vikrant; Avinash, K.; Sen, A.

    2012-09-15

    A model for the dust cluster explosion where micron/sub-micron sized particles are accelerated at the expense of plasma thermal energy, in the afterglow phase of a complex plasma discharge is proposed. The model is tested by molecular dynamics simulations of dust particles in a confining potential. The nature of the explosion (caused by switching off the discharge) and the concomitant dust acceleration is found to depend critically on the pressure of the background neutral gas. At low gas pressure, the explosion is due to unshielded Coulomb repulsion between dust particles and yields maximum acceleration, while in the high pressure regime it is due to shielded Yukawa repulsion and yields much feebler acceleration. These results are in agreement with experimental findings. Our simulations also confirm a recently proposed electrostatic (ES) isothermal scaling relation, P{sub E}{proportional_to}V{sub d}{sup -2} (where P{sub E} is the ES pressure of the dust particles and V{sub d} is the confining volume).

  13. Conveyor dust control

    SciTech Connect

    Goldbeck, L.

    1999-11-01

    In the past, three different approaches have been used to control dust arising at conveyor load zones. They are: Dust Containment consists of those mechanical systems employed to keep material inside the transfer point with the main material body. Dust Suppression systems increase the mass of suspended dust particles, allowing them to fall from the air stream. Dust Collection is the mechanical capture and return of airborne material after it becomes airborne from the main material body. Previously, these three approaches have always been seen as separate entities. They were offered by separate organizations competing in the marketplace. The three technologies vied for their individual piece of the rock, at the expense of the other technologies (and often at the expense of overall success). There have been considerable amounts of I`m better selling, as well as finger pointing at the other systems when problems arose. Each system claimed its own technology was the best, providing the most effective, most cost-efficient, most maintenance-free solution to fugitive material.

  14. The Ulysses dust experiment

    NASA Technical Reports Server (NTRS)

    Gruen, E.; Fechtig, H.; Giese, R. H.; Kissel, J.; Maas, D.; McDonnell, A. M.; Morfill, G.; Schwehm, G.; Zook, H. A.

    1992-01-01

    The Ulysses dust experiment is intended to provide direct observations of dust grains with masses between 10(exp -16) g and 10(exp -6) g in interplanetary space, to investigate their physical and dynamical properties as functions of heliocentric distance and ecliptic latitude. Of special interest is the question of what portion is provided by comets, asteroids and interstellar particles. The investigation is performed with an instrument that measures the mass, speed, flight direction, and electric charge of individual dust particles. It is a multicoincidence detector with a mass sensitivity 10(exp 6) times higher than that of previous in-situ experiments which measured dust in the outer solar system. The instrument weighs 3.8 kg, consumes 2.2 W, and has a normal data transmission rate of 8 bits/s in nominal spacecraft tracking mode. On 27 Oct. 1990 the instrument was switched on. The instrument was configured to flight conditions, and science data collection started immediately. At least 44 dust impacts had been recorded by 13 Jan. 1991. Flux values are given covering the heliocentric distance range from 1.04 to 1.7 AU.

  15. Oblique dust density waves

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Arp, Oliver; Menzel, Kristoffer; Klindworth, Markus

    2007-11-01

    We report on experimental observations of dust density waves in a complex (dusty) plasma under microgravity. The plasma is produced in a radio-frequency parallel-plate discharge (argon, p=15Pa, U=65Vpp). Different sizes of dust particles were used (3.4 μm and 6.4μm diameter). The low-frequency (f 11Hz) dust density waves are naturally unstable modes, which are driven by the ion flow in the plasma. Surprisingly, the wave propagation direction is aligned with the ion flow direction in the bulk plasma but becomes oblique at the boundary of the dust cloud with an inclination of 60^o with respect to the plasma boundary. The experimental results are compared with a kinetic model in the electrostatic approximation [1] and a fluid model [2]. Moreover, the role of dust surface waves is discussed. [1] M. Rosenberg, J. Vac. Sci. Technol. A 14, 631 (1996) [2] A. Piel et al, Phys. Rev. Lett. 97, 205009 (2006)

  16. Dust Streams from Tunisia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On October 6, 2001, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) captured this true-color image of a large dust storm blowing northeastward across the Mediterranean Sea from Tunisia. According to Joseph Prospero, professor of atmospheric science at the University of Miami, there is an unusual arc-shaped 'front' to the dust cloud. The storm's shape suggests that the source of the dust is rather small and that the meteorology driving it rather unusual. The dust seems to be coming out of the wadis, dry lakebeds and riverbeds, at the base of the Tell Atlas Mountains in northern Tunisia and eastern Algeria. The dust appears to be blowing toward the island of Sicily, Italy (toward the upper righthand corner). Also notice there is a relatively thin plume of smoke emanating eastward from the top of Mount Etna on Sicily. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  17. The global distribution of mineral dust and its impacts on the climate system: A review

    NASA Astrophysics Data System (ADS)

    Choobari, O. Alizadeh; Zawar-Reza, P.; Sturman, A.

    2014-03-01

    Mineral dust aerosols, the tiny soil particles suspended in the atmosphere, have a key role in the atmospheric radiation budget and hydrological cycle through their radiative and cloud condensation nucleus effects. Current understanding of spatial and temporal variations of mineral dust, as well as its impacts on the climate system and cloud properties is outlined. Mineral dust aerosols are blown into the atmosphere mainly from arid and semi-arid regions where annual rainfall is extremely low and substantial amounts of alluvial sediment have been accumulated over long periods. They are subject to long-range transport of an intercontinental scale, including North African dust plumes over the Atlantic Ocean, summer dust plumes from the Arabian Peninsula over the Arabian Sea and Indian Ocean and spring dust plumes from East Asia over the Pacific Ocean. Mineral dust aerosols influence the climate system and cloud microphysics in multiple ways. They disturb the climate system directly by scattering and partly absorbing shortwave and longwave radiation, semi-directly by changing the atmospheric cloud cover through evaporation of cloud droplets (i.e. the cloud burning effect), and indirectly by acting as cloud and ice condensation nuclei, which changes the optical properties of clouds (i.e. the first indirect effect), and may decrease or increase precipitation formation (i.e. the second indirect effect). Radiative forcing by mineral dust is associated with changes in atmospheric dynamics that may change the vertical profile of temperature and wind speed, through which a feedback effect on dust emission can be established.

  18. Dust transport and deposition observed from the Terra-MODIS space observations

    NASA Astrophysics Data System (ADS)

    Kaufman, Y. J.; Koren, I.; Tanre, D.; Fan, S.; Remer, L.; Ginoux, P.

    2003-12-01

    Meteorological observations, in situ data and satellite images of dust episodes were used already in the 1970s to estimate that 100 tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but deteriorates air quality and caries pathogens as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport and deposition. The Terra spacecraft launched at the dawn of the last millennium provides first systematic well calibrated multispectral measurements from the MODIS instrument, for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and evaluate the African dust column concentration, transport and deposition. We found that 230 80 tg of dust are transported annually from Africa to the Atlantic Ocean, 30 tg return to Africa and Europe, 70 tg reach the Caribbean, 45 tg fertilize the Amazon Basin, 4 times as previous estimates thus explaining a paradox regarding the source of nutrition to the Amazon forest, and 120 40 tg are deposited in the Atlantic Ocean. The results are compared favorably with dust transport models for particle radius * 12 m. This study is a first example of quantitative use of MODIS aerosol for a geophysical study.

  19. Dust Growth by RF Sputtering

    SciTech Connect

    Churton, B.; Samarian, A. A.; Coueedel, L.

    2008-09-07

    The effect of the dust particle growth by RF sputtering on glow discharge has been investigated. It has been found that the growth of dust particles modifies the electrical characteristics of the discharge. In particularly, the absolute value of the self-bias voltage decreases during the particle growth due to the electron losses on the dust particles. To find the correlation between the dust growth and the self bias evolution, dust particles have been collected at different times. The dust particle growth rate is found to be linear.

  20. How outbreaks of infectious disease are detected: a review of surveillance systems and outbreaks.

    PubMed Central

    Dato, Virginia; Wagner, Michael M.; Fapohunda, Abi

    2004-01-01

    To learn how outbreaks of infectious disease are detected and to describe the entities and information systems that together function to identify outbreaks in the U.S., the authors drew on multiple sources of information to create a description of existing surveillance systems and how they interact to detect outbreaks. The results of this analysis were summarized in a system diagram. The authors reviewed a sample of recent outbreaks to determine how they were detected, with reference to the system diagram. The de facto U.S. system for detection of outbreaks consists of five components: the clinical health care system, local/state health agencies, federal agencies, academic/professional organizations, and collaborating governmental organizations. Primary data collection occurs at the level of clinical health care systems and local health agencies. The review of a convenience sample of outbreaks showed that all five components of the system participated in aggregating, analyzing, and sharing data. The authors conclude that the current U.S. approach to detection of disease outbreaks is complex and involves many organizations interacting in a loosely coupled manner. State and local health departments and the health care system are major components in the detection of outbreaks. PMID:15313109

  1. Measles & rubella outbreaks in Maharashtra State, India

    PubMed Central

    Vaidya, Sunil R.; Kamble, Madhukar B.; Chowdhury, Deepika T.; Kumbhar, Neelakshi S.

    2016-01-01

    Background & objectives: Under the outbreak-based measles surveillance in Maharashtra State the National Institute of Virology at Pune receives 3-5 serum samples from each outbreak and samples from the local hospitals in Pune for laboratory diagnosis. This report describes one year data on the measles and rubella serology, virus isolation and genotyping. Methods: Maharashtra State Health Agencies investigated 98 suspected outbreaks between January-December 2013 in the 20 districts. Altogether, 491 serum samples were received from 20 districts and 126 suspected cases from local hospitals. Samples were tested for the measles and rubella IgM antibodies by commercial enzyme immunoassay (EIA). To understand the diagnostic utility, a subset of serum samples (n=53) was tested by measles focus reduction neutralization test (FRNT). Further, 37 throat swabs and 32 urine specimens were tested by measles reverse transcription (RT)-PCR and positive products were sequenced. Virus isolation was performed in Vero hSLAM cells. Results: Of the 98 suspected measles outbreaks, 61 were confirmed as measles, 12 as rubella and 21 confirmed as the mixed outbreaks. Four outbreaks remained unconfirmed. Of the 126 cases from the local hospitals, 91 were confirmed for measles and three for rubella. Overall, 93.6 per cent (383/409) confirmed measles cases were in the age group of 0-15 yr. Measles virus was detected in 18 of 38 specimens obtained from the suspected cases. Sequencing of PCR products revealed circulation of D4 (n=9) and D8 (n=9) strains. Four measles viruses (three D4 & one D8) were isolated. Interpretation & conclusions: Altogether, 94 measles and rubella outbreaks were confirmed in 2013 in the State of Maharasthra indicating the necessity to increase measles vaccine coverage in the State. PMID:27121521

  2. Forecasting fluctuating outbreaks in seasonally driven epidemics

    NASA Astrophysics Data System (ADS)

    Stone, Lewi

    2009-03-01

    Seasonality is a driving force that has major impact on the spatio-temporal dynamics of natural systems and their populations. This is especially true for the transmission of common infectious diseases such as influenza, measles, chickenpox, and pertussis. Here we gain new insights into the nonlinear dynamics of recurrent diseases through the analysis of the classical seasonally forced SIR epidemic model. Despite many efforts over the last decades, it has been difficult to gain general analytical insights because of the complex synchronization effects that can evolve between the external forcing and the model's natural oscillations. The analysis advanced here attempts to make progress in this direction by focusing on the dynamics of ``skips'' where we identify and predict years in which the epidemic is absent rather than outbreak years. Skipping events are intrinsic to the forced SIR model when parameterised in the chaotic regime. In fact, it is difficult if not impossible to locate realistic chaotic parameter regimes in which outbreaks occur regularly each year. This contrasts with the well known Rossler oscillator whose outbreaks recur regularly but whose amplitude vary chaotically in time (Uniform Phase Chaotic Amplitude oscillations). The goal of the present study is to develop a ``language of skips'' that makes it possible to predict under what conditions the next outbreak is likely to occur, and how many ``skips'' might be expected after any given outbreak. We identify a new threshold effect and give clear analytical conditions that allow accurate predictions. Moreover, the time of occurrence (i.e., phase) of an outbreak proves to be a useful new parameter that carries important epidemiological information. In forced systems, seasonal changes can prevent late-initiating outbreaks (i.e., having high phase) from running to completion. These principles yield forecasting tools that should have relevance for the study of newly emerging and reemerging diseases.

  3. 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

  4. Dust properties from scattering

    NASA Astrophysics Data System (ADS)

    Lefèvre, C.; Pagani, L.; Min, M.; Poteet, C.; Whittet, D.; Cambrésy, L.

    2016-05-01

    Dust grains evolve during the life cycle of the interstellar matter. From their birth places to dense molecular clouds, they grow by coagulation and acquire ice mantles, mainly composed of water. These morphological changes affect their optical properties. However, it remains a highly degenerate issue to determine their composition, size distribution, and shape from observations. In particular, using wavelengths associated to dust emission alone is not sufficient to investigate dense cold cores. Fortunately, scattering has turned out to be a powerful tool to investigate molecular clouds from the outer regions to the core. In particular, it is possible to quantify the amount of dust aggregates needed to reproduce observations from 1.25 to 8 μm.

  5. Big Dust Devils

    NASA Technical Reports Server (NTRS)

    2005-01-01

    28 January 2004 Northern Amazonis Planitia is famous for its frequent, large (> 1 km high) dust devils. They occur throughout the spring and summer seasons, and can be detected from orbit, even at the 240 meters (278 yards) per pixel resolution of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments. This red wide angle image shows a plethora of large dust devils. The arrow points to an example. Shadows cast by the towering columns of swirling dust point away from the direction of sunlight illumination (sun is coming from the left/lower left). This December 2004 scene covers an area more than 125 km (> 78 mi) across and is located near 37oN, 154oW.

  6. Polar Dust Devil Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    30 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of dunes in the martian north polar region is important because it shows one of the highest northern latitude views of streaks thought to be made by passing dust devils. The dark, thin, filamentary streaks on the dunes and on the adjacent plains were probably formed by dust devils. The dunes occur near 76.6oN, 62.7oW. Dust devil streaks are observed on Mars at very high latitudes, such as this, all the way down to the equator. They are also seen at all elevations, from the deepest parts of the Hellas Basin to the summit of Olympus Mons. This picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  7. Dust control for draglines

    SciTech Connect

    Grad, P.

    2009-09-15

    Monitoring dust levels inside draglines reveals room for improvement in how filtration systems are used and maintained. The Australian firm BMT conducted a field test program to measure airflow parameters, dust fallout rates and dust concentrations, inside and outside the machine house, on four draglines and one shovel. The study involved computational fluid dynamics (CFD) simulations. The article describes how the tests were made and gives results. It was not possible to say which of the two main filtration systems currently used on Australian draglines - Dynavane or Floseps - performs better. It would appear that more frequent maintenance and cleaning would increase the overall filtration performance and systems could be susceptible to repeat clogging in a short time. 2 figs., 1 photos.

  8. How important are cyclones for emitting mineral dust aerosol in North Africa?

    NASA Astrophysics Data System (ADS)

    Fiedler, S.; Schepanski, K.; Knippertz, P.; Heinold, B.; Tegen, I.

    2013-12-01

    This study presents the first quantitative estimate of the mineral dust emission associated to atmospheric depressions and migrating, long-lived cyclones in North Africa. Results from a tracking algorithm are combined with dust emission flux calculations based on ERA-Interim data from the European Centre for Medium-Range Weather Forecasts for 1989-2008. The results highlight that depressions are abundant and associated with 55% of the dust emission amount annually and spatially averaged over North African dust sources. Even larger contributions to dust emission from depressions are found south of the Atlas Mountains during spring with regionally up to 90%. It is spring when the largest monthly totals of 250-380 g m-2 of dust emission occur in North Africa. The remaining months have a total dust emission smaller than 80 g m-2. In summer, depressions, particularly Saharan heat lows, coincide with up to 90% of the seasonal total dust emission over wide areas of North Africa. In contrast to depressions, migrating cyclones that live for more than two days are rare and are associated to 4% of the annual and spatial dust emission average. Migrating cyclones over North Africa occur primarily in spring north of 20° N with eastwards trajectories and typical life times of three to seven days. Regionally larger seasonal totals of dust emission are associated to cyclones with up to 25% over Libya. In summer, near-surface signatures of African Easterly Waves (AEWs) emit regionally up to 15% of the total emission. The diurnal cycle of dust emission underlines that emission associated to cyclones at mid-day is substantially larger than at night by a factor of three to five. Soil moisture weakens dust emission during cyclone passage by 10%. Despite the overall small contribution of migrating cyclones to dust emission, cyclones coincide with particularly intense dust emission events exceeding the climatological mean flux by a factor of four to eight. This implies, that both

  9. Tikhonravov Crater Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Dust avalanches, also called slope streaks, occur on many Martian terrains. The deposition of airborne dust on surfaces causes a bright tone in the THEMIS VIS images. Any movement of the dust downhill, a dust avalanche, will leave behind a streak where the darker, dust-free surface is exposed.

    These dust avalanches are located within a small crater inside Tikhonravov Crater.

    Image information: VIS instrument. Latitude 12.6, Longitude 37.1 East (322.9 West). 36 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Lycus Sulci Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Dust avalanches, also called slope streaks, occur on many Martian terrains. The deposition of airborne dust on surfaces causes a bright tone in the THEMIS VIS images. Any movement of the dust downhill, a dust avalanche, will leave behind a streak where the darker, dust-free surface is exposed.

    These dust avalanches occur on the slopes of Lycus Sulci near Olympus Mons.

    Image information: VIS instrument. Latitude 28.1, Longitude 220.4 East (139.6 West). 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Crater Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Dust avalanches, also called slope streaks, occur on many Martian terrains. The deposition of airborne dust on surfaces causes a bright tone in the THEMIS VIS images. Any movement of the dust downhill, a dust avalanche, will leave behind a streak where the darker, dust-free surface is exposed.

    These dust avalanches are located in a small canyon within a crater rim northeast of Naktong Vallis.

    Image information: VIS instrument. Latitude 7.1, Longitude 34.7 East (325.3 West). 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Crater Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Dust avalanches, also called slope streaks, occur on many Martian terrains. The deposition of airborne dust on surfaces causes a bright tone in the THEMIS VIS images. Any movement of the dust downhill, a dust avalanche, will leave behind a streak where the darker, dust-free surface is exposed.

    This region of dust avalanches is located in and around a crater to the west of yesterday's image.

    Image information: VIS instrument. Latitude 14.7, Longitude 32.7 East (327.3 West). 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  13. Analysis of Measurements of Saharan Dust by Airborne and Ground-based Remote Sensing Methods during the Puerto Rico Dust Experiment (PRIDE)

    NASA Technical Reports Server (NTRS)

    Reid, Jeffrey S.; Kinney, James E.; Westphal, Douglas L.; Holben, Brent N.; Welton, E. Judd; Tsay, Si-Chee; Eleuterio, Daniel P.; Campbell, James; Christopher, Sundar A.; Jonsson, Haflidi H.

    2003-01-01

    For 26 days in mid-June and July 2000, a research group comprised of U.S. Navy, NASA, and university scientists conducted the Puerto Rico Dust Experiment (PRIDE). In this paper we give a brief overview of mean meteorological conditions during the study. We focus on findings on African dust transported into the Caribbean utilizing Navajo aircraft and AERONET Sun photometer data. During the study midvisible aerosol optical thickness (AOT) in Puerto Rico averaged 0.25, with a maximum less than 0.5 and with clean marine periods of _0.08. Dust AOTs near the coast of Africa (Cape Verde Islands and Dakar) averaged _0.4, 30% less than previous years. By analyzing dust vertical profiles in addition to supplemental meteorology and MPLNET lidar data we found that dust transport cannot be easily categorized into any particular conceptual model. Toward the end of the study period, the vertical distribution of dust was similar to the commonly assumed Saharan Air Layer (SAL) transport. During the early periods of the study, dust had the highest concentrations in the marine and convective boundary layers with only a, weak dust layer in the SAL being present, a state usually associated with wintertime transport patterns. We corroborate the findings of Maring et al. that in most cases, there was an unexpected lack of vertical stratification of dust particle size. We systematically analyze processes which may impact dust vertical distribution and determine and speculate that dust vertical distribution predominately influenced by flow patterns over Africa and differential advection couple with mixing by easterly waves and regional subsidence.

  14. Analysis of measurements of Saharan dust by airborne and ground-based remote sensing methods during the Puerto Rico Dust Experiment (PRIDE)

    NASA Astrophysics Data System (ADS)

    Reid, Jeffrey S.; Kinney, James E.; Westphal, Douglas L.; Holben, Brent N.; Welton, Ellsworth J.; Tsay, Si-Chee; Eleuterio, Daniel P.; Campbell, James R.; Christopher, Sundar A.; Colarco, P. R.; Jonsson, Haflidi H.; Livingston, John M.; Maring, Hal B.; Meier, Michael L.; Pilewskie, Peter; Prospero, Joseph M.; Reid, Elizabeth A.; Remer, Lorraine A.; Russell, Philip B.; Savoie, Dennis L.; Smirnov, Alexander; Tanré, Didier

    2003-10-01

    For 26 days in mid-June and July 2000, a research group comprised of U.S. Navy, NASA, and university scientists conducted the Puerto Rico Dust Experiment (PRIDE). In this paper we give a brief overview of mean meteorological conditions during the study. We focus on our findings on African dust transported into the Caribbean utilizing a Navajo aircraft and AERONET Sun photometer data. During the study midvisible aerosol optical thickness (AOT) in Puerto Rico averaged 0.25, with a maximum >0.5 and with clean marine periods of ˜0.08. Dust AOTs near the coast of Africa (Cape Verde Islands and Dakar) averaged ˜0.4, 30% less than previous years. By analyzing dust vertical profiles in addition to supplemental meteorology and MPLNET lidar data we found that dust transport cannot be easily categorized into any particular conceptual model. Toward the end of the study period, the vertical distribution of dust was similar to the commonly assumed Saharan Air Layer (SAL) transport. During the early periods of the study, dust had the highest concentrations in the marine and convective boundary layers with only a weak dust layer in the SAL being present, a state usually associated with wintertime transport patterns. We corroborate the findings of [2003] that in most cases, there was an unexpected lack of vertical stratification of dust particle size. We systematically analyze processes that may impact dust vertical distribution and speculate that dust vertical distribution predominately influenced by flow patterns over Africa and differential advection coupled with fair weather cloud entrainment, mixing by easterly waves, and regional subsidence.

  15. Ebola virus disease outbreak; the role of field epidemiology training programme in the fight against the epidemic, Liberia, 2014

    PubMed Central

    Lubogo, Mutaawe; Donewell, Bangure; Godbless, Lucas; Shabani, Sasita; Maeda, Justin; Temba, Herilinda; Malibiche, Theophil C; Berhanu, Naod

    2015-01-01

    The African Field Epidemiology Network (AFENET) is a public health network established in 2005 as a non-profit networking alliance of Field Epidemiology and Laboratory Training Programs (FELTPs) and Field Epidemiology Training Programs (FETPs) in Africa. AFENET is dedicated to supporting Ministries of Health in Africa build strong, effective and sustainable programs and capacity to improve public health systems by partnering with global public health experts. The Network's goal is to strengthen field epidemiology and public health laboratory capacity to contribute effectively to addressing epidemics and other major public health problems in Africa. The goal for the establishment of FETP and FELTP was and still is to produce highly competent multi-disciplinary public health professionals who would assume influential posts in the public health structures and tackle emerging and re-emerging communicable and non-communicable diseases. AFENET currently networks 12 FELTPs and FETPs in sub-Saharan Africa with operations in 20 countries. During the Ebola Virus Disease (EVD) outbreak in West Africa, African Union Support for the Ebola Outbreak in West Africa (ASEOWA) supported FETP graduates from Uganda, Zimbabwe, Ethiopia and Tanzania for the investigation and control of the EVD outbreak in Liberia. The graduates were posted in different counties in Liberia where they lead teams of other experts conduct EVD outbreak investigations, Infection Control and Prevention trainings among health workers and communities, Strengthening integrated disease surveillance, developing Standard Operating Procedures for infection control and case notification in the Liberian setting as well as building capacity of local surveillance officers’ conduct outbreak investigation and contact tracing. The team was also responsible for EVD data management at the different Counties in Liberia. The FETP graduates have been instrumental in the earlier successes registered in various counties in

  16. Electric Activity in Dust Devils and Dust Storms

    NASA Astrophysics Data System (ADS)

    Renno, R. O.; Yana, C.; Covert, A.; Renno, K.; Wilson, J.

    2005-12-01

    Terrestrial dust devils produce charge separation and electric fields that exceeds the breakdown potential of the thin Martian atmosphere (Farrell et al., 2002, 2003; Krauss et al., 2002; Renno et al., 2004). Typical Martian dust devils are wider, taller and have larger dust content than terrestrial vortices. Thus, charge separation and electric-field breakdown are likely to occur in Martian dust devils and dust storms. We show that theory, laboratory experiments, and field measurements in Arizona suggests that collisions between sand and dust particles at the bottom of dust devils produce non-thermal microwave radiation. The non-thermal microwave emission allows not only the indirect detection of electric activity but could also allow the determination of the physical properties of Martian sand and dust by remote sensing. Besides being geologically important, electrically charged Martian dust devils and dust storms are potential hazards to Landers and at minimum would be an annoyance to future astronauts exploring the planet. Indeed, the design of adequate mechanical and electrical systems for these Landers cannot progress effectively without a better understanding of Martian dust devils and dust storms. Moreover, ancillary phenomena associated with electrically charged vortices can ionize atmospheric gases and might have important implications for atmosphere chemistry and even habitability.

  17. Sabaeus Dust Devil

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-546, 16 November 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an active dust devil in Sinus Sabaeus, southeast of Schiaparelli Basin. Sunlight illuminates the scene from the upper left (northwest). The dust devil is best recognized by the dark, columnar shadow it casts toward the lower right (southeast). This image is located near 5.4oS, 340.0oW. The area shown is about 3 km (1.9 mi) wide.

  18. Syrian Dust Devil

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust devil in far western Syria Planum. The dust devil is located near the left-center of the image. It is casting a shadow toward the lower right (southeast).

    Location near: 14.5oS, 109.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Winter

  19. Dust Devil Days

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 6 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    Dust devils, small cyclonic wind storms, are common in the American Southwest and on Mars. As the dust devil moves across the surface it picks up the loose dust, leaving behind a dark track to mark its passage. These dust devil tracks are in the Argyre Basin.

    Image information: VIS instrument. Latitude -46.6, Longitude 317.5 East (42.5 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin

  20. Dust Devils Together

    NASA Technical Reports Server (NTRS)

    2005-01-01

    14 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired during northern summer in November 2004, shows a group of three large afternoon dust devils occurring within several kilometers of each other in northwestern Amazonis. The image covers an area 3 km (1.9 mi) wide and was obtained with a spatial resolution of 12 meters (13 yards) per pixel. This scene is located near 36.2oN, 157.6oW. Sunlight illuminates the dust devils from the left.

  1. Tithonium Dust Devil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    23 June 2004 The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) captured this chance view of a dust devil (left of the center of the picture) near 2 p.m. local Mars time on 12 April 2004, in western Tithonium Chasma. The dark splotch to the right of the dust devil is its shadow. Sunlight illuminates the scene from the left/upper left. Tithonium is one of the troughs of the Valles Marineris system. The picture is located near 4.7oS, 89.1oW, and covers an area about 3 km (1.9 mi) wide.

  2. September Dust Devil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    8 September 2004 Presently Mars is experiencing late spring in its northern hemisphere, and dust devil activity is picking up as summer approaches. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of a cratered plain in southern Acidalia Planitia was acquired earlier this week on 5 September 2004. The arrow points to a dust devil observed that day. The image is located near 29.2oN, 30.3oW, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

  3. African and non-African admixture components in African Americans and an African Caribbean population.

    PubMed

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  4. Electrostatic Characterization of Lunar Dust

    NASA Technical Reports Server (NTRS)

    2008-01-01

    To ensure the safety and success of future lunar exploration missions, it is important to measure the toxicity of the lunar dust and its electrostatic properties. The electrostatic properties of lunar dust govern its behavior, from how the dust is deposited in an astronaut s lungs to how it contaminates equipment surfaces. NASA has identified the threat caused by lunar dust as one of the top two problems that need to be solved before returning to the Moon. To understand the electrostatic nature of lunar dust, NASA must answer the following questions: (1) how much charge can accumulate on the dust? (2) how long will the charge remain? and (3) can the dust be removed? These questions can be answered by measuring the electrostatic properties of the dust: its volume resistivity, charge decay, charge-to-mass ratio or chargeability, and dielectric properties.

  5. Dust Devils Whip by Spirit

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On sol 1120 (February 26, 2007), the navigation camera aboard NASA's Mars Exploration Rover Spirit captured one of the best dust devils it's seen in its three-plus year mission. The series of navigation camera images were put together to make a dust devil movie.

    The dust devil column is clearly defined and is clearly bent in the down wind direction. Near the end of the movie, the base of the dust devil becomes much wider. The atmospheric science team thinks that this is because the dust devil encountered some sand and therefore produced a 'saltation skirt,' an apron of material that is thrown out of the dust devil because it is too large to be carried up into suspension.

    Also near the end of the movie the dust devil seems to move faster across the surface. This is because Spirit began taking pictures less frequently, and not because the dust devil sped up.

  6. Estimation of Dust Emission from the Western Coastal Plains of Arabian Peninsula

    NASA Astrophysics Data System (ADS)

    Anisimov, Anatolii; Stenchikov, Georgiy

    2016-04-01

    This study is aimed at quantifying local-scale dust emission from the coastal areas of western Arabian Peninsula. The dust emitted from these areas is frequently deposited directly to the Red Sea, acting as an important component of the nutrient balance of marine ecosystems. Most chemicals including iron, phosphorus, and nitrogen are introduced to the Red Sea with airborne dust. This process is especially significant for the oligotrophic northern Red Sea, where nutrients from the Indian Ocean cannot reach and the nutrient supply from land river discharge is negligible. The dust deposition to the Red Sea associated with major dust storms was recently estimated to be about 6 Tg/yr, but this estimate does not account for local, small-scale dust outbreaks occurring during fair weather conditions or moderate winds. The seasonality and the magnitude of this nutrient supply are largely unknown. In the present study, we quantify dust emissions using the fine-scale off-line version-4 of the Community Land Model (CLM4) with the high-resolution datasets as input parameters. We examine the model sensitivity to the spatial resolution of input land cover and vegetation data, and compare the results with weather station observations and reanalysis to choose the best model configuration. The model results are shown to be in reasonable agreement with station visibility measurements and the frequency of dust event reports. To improve the spatial characteristics of dust emission, we apply two state-of-the-art dust source functions. We found that the source function based on measurements from SEVIRI satellite substantially improves the simulation results, being in good agreement with both reanalysis data and station measurements. We identify the major dust source hot-spot areas over the coastal plain and analyze the seasonal and diurnal variability of dust emissions. The annual dust generation from the 145000 km2 coastal area reaches 6 Tg/yr. Roughly half of emitted dust could be

  7. The African superswell

    NASA Technical Reports Server (NTRS)

    Nyblade, Andrew A.; Robinson, Scott W.

    1994-01-01

    Maps of residual bathymetry in the ocean basins around the African continent reveal a broad bathymetric swell in the southeastern Atlantic Ocean with an amplitude of about 500 m. We propose that this region of anomalously shallow bathymetry, together with the contiguous eastern and southern African plateaus, form a superswell which we refer to as the African superswell. The origin of the African superswell is uncertain. However, rifting and volcanism in eastern Africa, as well as heat flow measurements in southern Africa and the southeastern Atlantic Ocean, suggest that the superswell may be attributed, at least in part, to heating of the lithosphere.

  8. A global satellite view of the seasonal distribution of mineral dust and its correlation with atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Alizadeh-Choobari, O.; Sturman, A.; Zawar-Reza, P.

    2014-12-01

    Aerosols make a considerable contribution to the climate system through their radiative and cloud condensation nuclei effects, which underlines the need for understanding the origin of aerosols and their transport pathways. Seasonal distribution of mineral dust around the globe and its correlation with atmospheric circulation is investigated using satellite data, and meteorological data from ECMWF. The most important sources of dust are located in North Africa, the Middle East and Southwest Asia with an observed summer maximum, and East Asia with a spring peak. Maximum dust activity over North Africa and the Middle East in summer is attributed to dry convection associated with the summertime low-pressure system, while unstable weather and dry conditions are responsible for the spring peak in dust emission in East Asia. Intercontinental transport of mineral dust by atmospheric circulation has been observed, including trans-Atlantic transport of North African dust, trans-Pacific transport of Asian dust, and transport of dust from the Middle East across the Indian Ocean. The extent of African dust over the Atlantic Ocean and its latitudinal variation with season is related to the large-scale atmospheric circulation, including seasonal changes in the position of the intertropical convergence zone (ITCZ) and variation of wind patterns. North African aerosols extend over longer distances across the North Atlantic in summer because of greater dust emission, an intensified easterly low level jet (LLJ) and strengthening of the Azores-Bermuda anticyclonic circulation. Transport of East Asian aerosol is facilitated by the existence of a LLJ that extends from East Asia to the west coast of North America.

  9. Ground-based Measurement Of Saharan Dust In Marine Environment

    NASA Astrophysics Data System (ADS)

    Jeong, M. J.; Ji, Q.; Tsay, S.; Hsu, C.; Hansell, R. A.; Augustine, D.

    2007-12-01

    An extensive field experiment, named NASA African Monsoon Multidisciplinary Analyses (NAMMA) was conducted during August-September of 2006 to investigate the genesis and development of hurricanes. Two ground-based mobile laboratories, Surface-sensing Measurements for Atmospheric Radiative Transfer (SMART) and Chemical, Optical, Microphysical Measurements of In-situ Troposphere (COMMIT), were deployed at Sal Island, Cape Verde to continuously monitor the structure and composition of the atmosphere in the major path of the Saharan Air Layer and the African Easterly Waves. A Micro-Pulse Lidar in SMART, which measures the vertical profiles of backscatter from the atmospheric particulates continuously, caught several episodes of Saharan dust layers reached the surface site. Simultaneously, physical and optical properties of aerosols (e.g., mixture of the Saharan dust and maritime aerosols) were captured by several instruments in COMMIT. In this study, we propose a novel method to separate dust properties from those of marine background aerosols by utilizing the synergy of a suite of in-situ measurements. Derived parameters are mass scattering coefficients and single scattering albedo (SSA) for dust near the surface (~10m). As a crosscheck, the SSA based on the surface measurements is compared with the result of Deep Blue satellite-based aerosol retrievals, which is now incorporated in the operational MODIS aerosol product. The presented preliminary results will be useful in studying the properties of Saharan dust originated from various source regions, which, in turns, can be used as inputs to aerosol transport models to help better understand the interactions between aerosol and cloud water cycle.

  10. Circumstellar, Cometary and Interplanetary Dust

    NASA Astrophysics Data System (ADS)

    Crovisier, J.

    2000-11-01

    The Infrared Space Observatory made us available for the first time the full infrared spectrum of cosmic dust in a variety of astrophysical environments. I review what we learned from ISO on the composition of dust in the Solar System (cometary and interplanetary) and in circumstellar discs around young or evolved stars, what are the commonalities and parallels between dust in these different environments, and what this tells us on the cosmic dust cycle.

  11. Investigating Sensitivity to Saharan Dust in Tropical Cyclone Formation Using Nasa's Adjoint Model

    NASA Technical Reports Server (NTRS)

    Holdaway, Daniel

    2015-01-01

    As tropical cyclones develop from easterly waves coming of the coast of Africa they interact with dust from the Sahara desert. There is a long standing debate over whether this dust inhibits or advances the developing storm and how much influence it has. Dust can surround the storm and absorb incoming solar radiation, cooling the air below. As a result an energy source for the system is potentially diminished, inhibiting growth of the storm. Alternatively dust may interact with clouds through micro-physical processes, for example by causing more moisture to condense, potentially increasing the strength. As a result of climate change, concentrations and amount of dust in the atmosphere will likely change. It it is important to properly understand its effect on tropical storm formation. The adjoint of an atmospheric general circulation model provides a very powerful tool for investigating sensitivity to initial conditions. The National Aeronautics and Space Administration (NASA) has recently developed an adjoint version of the Goddard Earth Observing System version 5 (GEOS-5) dynamical core, convection scheme, cloud model and radiation schemes. This is extended so that the interaction between dust and radiation is also accounted for in the adjoint model. This provides a framework for examining the sensitivity to dust in the initial conditions. Specifically the set up allows for an investigation into the extent to which dust affects cyclone strength through absorption of radiation. In this work we investigate the validity of using an adjoint model for examining sensitivity to dust in hurricane formation. We present sensitivity results for a number of systems that developed during the Atlantic hurricane season of 2006. During this period there was a significant outbreak of Saharan dust and it is has been argued that this outbreak was responsible for the relatively calm season. This period was also covered by an extensive observation campaign. It is shown that the

  12. Histoplasmosis outbreak associated with the renovation of an old house - Quebec, Canada, 2013.

    PubMed

    2014-01-01

    On May 19, 2013, a consulting physician contacted the Laurentian Regional Department of Public Health (Direction de santé publique des Laurentides [DSP]) in Quebec, Canada, to report that two masons employed by the same company to do demolition work were experiencing cough and dyspnea accompanied by fever. Other workers also were said to be ill. DSP initiated a joint infectious disease, environmental health, and occupational health investigation to determine the extent and cause of the outbreak. The investigation identified 14 persons with respiratory symptoms among 30 potentially exposed persons. A strong correlation was found between exposure to demolition dust containing bat or bird droppings and a diagnosis of histoplasmosis. Temporary suspension of construction work at the demolition site in Saint-Eustache, Quebec, northwest from Montreal, and transport of the old masonry elements to a secure site for burial were ordered, and information about the disease was provided to workers and residents. To prevent future outbreaks, recommendations included disinfection of any contaminated material, disposal of waste material with proper control of aerosolized dust, and mandatory use of personal protective equipment such as gloves, protective clothing, and adequate respirators. PMID:24381077

  13. Ice Nucleating Particle Properties in the Saharan Air Layer Close to the Dust Source

    NASA Astrophysics Data System (ADS)

    Boose, Y.; Garcia, I. M.; Rodríguez, S.; Linke, C.; Schnaiter, M.; Nickovic, S.; Lohmann, U.; Kanji, Z. A.; Sierau, B.

    2015-12-01

    In August 2013 and 2014 measurements of ice nucleating particle (INP) concentrations, aerosol particle size distributions, chemistry and fluorescence were conducted at the Izaña Atmospheric Observatory located at 2373 m asl on Tenerife, west off the African shore. During summer, the observatory is frequently within the Saharan Air Layer and thus often exposed to dust. Absolute INP concentrations and activated fractions at T=-40 to -15°C and RHi=100-150 % were measured. In this study, we discuss the in-situ measured INP properties with respect to changes in the chemical composition, the biological content, the source regions as well as transport pathways and thus aging processes of the dust aerosol. For the first time, ice crystal residues were also analyzed with regard to biological content by means of their autofluorescence signal close to a major dust source region. Airborne dust samples were collected with a cyclone for additional offline analysis in the laboratory under similar conditions as in the field. Both, in-situ and offline dust samples were chemically characterized using single-particle mass spectrometry. The DREAM8 dust model extended with dust mineral fractions was run to simulate meteorological and dust aerosol conditions for ice nucleation. Results show that the background aerosol at Izaña was dominated by carbonaceous particles, which were hardly ice-active under the investigated conditions. When Saharan dust was present, INP concentrations increased by up to two orders of magnitude even at water subsaturated conditions at T≤-25°C. Differences in the ice-activated fraction were found between different dust periods which seem to be linked to variations in the aerosol chemical composition (dust mixed with changing fractions of sea salt and differences in the dust aerosol itself). Furthermore, two biomass burning events in 2014 were identified which led to very low INP concentrations under the investigated temperature and relative humidity

  14. Dust storm monitoring: effects on the environment, human health, and potential security conflicts

    NASA Astrophysics Data System (ADS)

    Davara, Fernando; de la Cruz, Antonio

    2004-10-01

    Monitoring dust storms with recently available medium and moderate resolution satellites (Meris, Modis and SeaWiFS) is providing new global information regarding the sources, transportation tracks and affected areas. Saharan dust plumes reach the SE region of the United States and the Caribbean region in summer and the Amazon basin in winter. Generally these Saharan plumes branch off in dust tracks along the North Atlantic reaching Western Europe as far north as the Scandinavian countries. Furthermore, dust storms originating in the Eastern Sahara and Northern African deserts form dust plumes propagated by the Sirocco winds that, after crossing the Mediterranean Sea, affect Southern and Central Europe particularly during spring and summer. Dust storms originating in the Gobi and Taklamakan deserts blow in an easterly direction propagating dust plumes affecting Korea, Japan and reach the United States after crossing the Pacific Ocean. The large amount of cyclic deposition generated by dust storms produces an environmental impact that causes the decay of coral reefs in the Caribbean, the origin and distribution of red tides and the disappearance of sea grasses. The relationship of dust plumes with the increasing number of asthma and allergy cases in the Caribbean correlates well with the appearance of similar cases in Europe and elsewhere during the mid 1980s. The recurrence presence of insecticides in regions where these products were banned long ago, or where they were never used, may be partly due to Saharan dust plumes. The loss of agricultural soil, literally blown away by dust storms in the source areas, creates hardship, hunger and forced-migration. Dust storms should be considered as an important security issue.

  15. Pneumonic Plague Outbreak, Northern Madagascar, 2011

    PubMed Central

    Richard, Vincent; Herindrainy, Perlinot; Soanandrasana, Rahelinirina; Ratsitoharina, Maherisoa; Rakotomanana, Fanjasoa; Andrianalimanana, Samuel; Scholz, Holger C.; Rajerison, Minoarisoa

    2015-01-01

    Yersinia pestis, the causative agent of plague, is endemic to Madagascar, particularly to the central highlands. Although plague has not been previously reported in northern Madagascar, an outbreak of pneumonic plague occurred in this remote area in 2011. Over a 27-day period, 17 suspected, 2 presumptive, and 3 confirmed human cases were identified, and all 15 untreated 20 patients died. Molecular typing of Y. pestis isolated from 2 survivors and 5 Rattus rattus rat samples identified the Madagascar-specific 1.ORI3-k single-nucleotide polymorphism genotype and 4 clustered regularly interspaced short palindromic repeat patterns. This outbreak had a case-fatality rate of 100% for nontreated patients. The Y. pestis 1.ORI3-k single-nucleotide polymorphism genotype might cause larger epidemics. Multidrug-resistant strains and persistence of the pathogen in natural foci near human settlements pose severe risks to populations in plague-endemic regions and require outbreak response strategies. PMID:25530466

  16. The Fifth Outbreak of Trichinosis in Korea

    PubMed Central

    Rhee, Ji-Young; Hong, Sung-Tae; Lee, Hye-Jung; Seo, Min

    2011-01-01

    Trichinosis is a food-borne zoonotic disease caused by the nematode, Trichinella spp., and had been reported several times in Korea. Recently, there was an additional outbreak, involving 5 patients, the findings from which are reported herein. On 30 November 2010, 8 persons ate sashimi of the meat of a wild boar. Then, 2-3 weeks later, they complained of myalgia and fever. Unfortunately, muscle biopsy was not performed, but ELISA was performed using their sera. Two people among 8 were positive for Trichinella on the 34th day post-infection (PI), and 3 patients who initially revealed negative ELISA were additionally proved to be positive for trichinosis on the 42nd day PI. Hence, the confirmed patients of trichinosis were 5 in total in the present outbreak. They were treated with albendazole and discharged uneventfully. This was the fifth outbreak of trichinosis in Korea. PMID:22355208

  17. Lessons from nosocomial viral haemorrhagic fever outbreaks.

    PubMed

    Fisher-Hoch, Susan P

    2005-01-01

    The outbreak of Marburg haemorrhagic fever in Angola in 2004-2005 shows once again the devastating and rapid spread of viral haemorrhagic fevers in medical settings where hygiene practices are poorly applied or ignored. The legacy of years of war and poverty in Angola has resulted in very poor medical education and services. The initial high rate of infection among infants in Angola may have been related to poor hospital practices, possibly administration of vaccines. Though the outbreak in Angola was in a part of Africa not previously known to have filovirus infection, prior ecological modelling had predicted this location and many others. Prevention of future outbreaks will not be easy. The urgent need is dissemination of knowledge and the training, discipline and resources for good clinical practice. Educating the public to demand higher standards could be a powerful tool. Good practices are difficult to establish and maintain on the scale needed. PMID:16373655

  18. Investigation of Outbreaks Complicated by Universal Exposure

    PubMed Central

    Bousema, Teun; Oliver, Isabel

    2012-01-01

    Outbreaks in which most or all persons were exposed to the same suspected source of infection, so-called universal exposure, are common. They represent a challenge for public health specialists because conducting analytical studies in such investigations is complicated by the absence of a nonexposed group. We describe different strategies that can support investigations of outbreaks with universal exposure. The value of descriptive epidemiology, extensive environmental investigation, and the hypothesis-generation phase cannot be overemphasized. An exposure that seems universal may in fact not be universal when additional aspects of the exposure are taken into account. Each exposure has unique characteristics that may not be captured when investigators rely on the tools readily at hand, such as standard questionnaires. We therefore encourage field epidemiologists to be creative and consider the use of alternative data sources or original techniques in their investigations of outbreaks with universal exposure. PMID:23092616

  19. Gusev Dust Devil, Sol 543

    NASA Technical Reports Server (NTRS)

    2005-01-01

    One dust devil scoots across the center of the view in this movie clip showing a few dust devils inside Mars' Gusev Crater. The clip consists of frames taken by the navigation camera on NASA's Mars Exploration Rover Spirit during the rover's 543rd martian day, or sol (July 13, 2005).

    Spirit began seeing dust devil activity around the beginning of Mars' spring season. Activity increased as spring continued, but fell off again for about two weeks during a dust storm. As the dust storm faded away, dust devil activity came back. In the mid-afternoons as the summer solstice approached, dust devils were a very common occurrence on the floor of Gusev crater. The early-spring dust devils tended to move southwest-to-northeast, across the dust devil streaks in Gusev seen from orbit. Increasingly as the season progresses, the dust devils are seen moving northwest-to-southeast, in the same direction as the streaks. Scientists are watching for the big dust devils that leave those streaks.

    In this clip, contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust moved by wind. The total time elapsed during the taking of these frames was 8 minutes, 21 seconds.

  20. Vacuum Head Removes Sanding Dust

    NASA Technical Reports Server (NTRS)

    Bengle, C. G.; Holt, J. W.

    1982-01-01

    Vacuum sander prevents sanding dust from entering a work area, since dust particles are drawn off as quickly as they are produced. Tool is useful where dust presents health hazards, interferes with such processes as semiconductor manufacture, or could destroy wet paint or varnish finishes. Could be used to sand such materials as lead paint.

  1. Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

    NASA Astrophysics Data System (ADS)

    Ansmann, A.; Seifert, P.; Tesche, M.; Wandinger, U.

    2012-10-01

    The polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajökull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvötn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

  2. Identification of a new strain of hepatitis E virus from an outbreak in Namibia in 1995.

    PubMed

    Maila, Hazel T; Bowyer, Sheila M; Swanepoel, Robert

    2004-01-01

    Endemic circulation of hepatitis E virus (HEV) in Namibia was suspected from serological data during an outbreak of non-A, non-B hepatitis in Rundu in 1995. The source of the outbreak was suspected to be the water supply, which had been compromised approximately 6 months earlier. Four HEV isolates from four different persons in this outbreak were successfully amplified, sequenced and analysed over a 451 bp region of a subgenomic fragment from the 3' end of the genome in ORF2. Phylogenetic analysis showed that the four Namibian HEV isolates clustered with a Mexican isolate in genotype II and shared 85.8-86.3 % nucleotide identity with the 1987 Mexican isolate, but were only 77.6-79.6 % similar to other African isolates. HEV isolated from the same region of Namibia in 1983 was reported to cluster in genotype I. However, virus isolates from sporadic cases of HEV isolated in 1997/8 in Nigeria were also from genotype II. PMID:14718623

  3. Detecting and Responding to a Dengue Outbreak: Evaluation of Existing Strategies in Country Outbreak Response Planning

    PubMed Central

    Kroeger, Axel; Runge-Ranzinger, Silvia; O'Dempsey, Tim

    2013-01-01

    Background. Dengue outbreaks are occurring with increasing frequency and intensity. Evidence-based epidemic preparedness and effective response are now a matter of urgency. Therefore, we have analysed national and municipal dengue outbreak response plans. Methods. Thirteen country plans from Asia, Latin America and Australia, and one international plan were obtained from the World Health Organization. The information was transferred to a data analysis matrix where information was extracted according to predefined and emerging themes and analysed for scope, inconsistencies, omissions, and usefulness. Findings. Outbreak response planning currently has a considerable number of flaws. Outbreak governance was weak with a lack of clarity of stakeholder roles. Late timing of responses due to poor surveillance, a lack of combining routine data with additional alerts, and lack of triggers for initiating the response weakened the functionality of plans. Frequently an outbreak was not defined, and early response mechanisms based on alert signals were neglected. There was a distinct lack of consideration of contextual influences which can affect how an outbreak detection and response is managed. Conclusion. A model contingency plan for dengue outbreak prediction, detection, and response may help national disease control authorities to develop their own more detailed and functional context specific plans. PMID:24222774

  4. Detecting and responding to a dengue outbreak: evaluation of existing strategies in country outbreak response planning.

    PubMed

    Harrington, Julia; Kroeger, Axel; Runge-Ranzinger, Silvia; O'Dempsey, Tim

    2013-01-01

    Background. Dengue outbreaks are occurring with increasing frequency and intensity. Evidence-based epidemic preparedness and effective response are now a matter of urgency. Therefore, we have analysed national and municipal dengue outbreak response plans. Methods. Thirteen country plans from Asia, Latin America and Australia, and one international plan were obtained from the World Health Organization. The information was transferred to a data analysis matrix where information was extracted according to predefined and emerging themes and analysed for scope, inconsistencies, omissions, and usefulness. Findings. Outbreak response planning currently has a considerable number of flaws. Outbreak governance was weak with a lack of clarity of stakeholder roles. Late timing of responses due to poor surveillance, a lack of combining routine data with additional alerts, and lack of triggers for initiating the response weakened the functionality of plans. Frequently an outbreak was not defined, and early response mechanisms based on alert signals were neglected. There was a distinct lack of consideration of contextual influences which can affect how an outbreak detection and response is managed. Conclusion. A model contingency plan for dengue outbreak prediction, detection, and response may help national disease control authorities to develop their own more detailed and functional context specific plans. PMID:24222774

  5. 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.

  6. Capabilities and Limitations of Space-Borne Passive Remote Sensing of Dust

    NASA Technical Reports Server (NTRS)

    Kalashnikova, Olga

    2008-01-01

    Atmospheric dust particles have significant effects on the climate and the environment and despite notable recent advances in modeling and observation, wind-blown dust radiative effects remain poorly quantified in both magnitude and sign [IPCC, 2001]. To address this issue, many scientists are using passive satellite observations to study dust properties and to constrain emission/transport models, because the information provided is both time-resolved and global in coverage. In order to assess the effects of individual dust outbreaks on atmospheric radiation and circulation, relatively high temporal resolution (of the order of hours or days) is required in the observational data. Data should also be available over large geographical areas, as dust clouds may cover hundreds of thousands of square kilometers and will exhibit significant spatial variation in their vertical structure, composition and optical properties, both between and within dust events. Spatial and temporal data continuity is necessary if the large-scale impact of dust loading on climate over periods ranging from hours to months is to be assessed.

  7. Saharan Dust Cloud

    Atmospheric Science Data Center

    2013-04-16

    ... was expected to produce dramatic sunsets and possibly a light coating of red-brown dust on vehicles from Florida to Texas. This image, ... far the most common non-spherical atmospheric aerosol, from pollution and forest fire particles, which are typically spherical. This image ...

  8. Dust Plumes off Libya

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Two-toned dust plumes blew northward off the coast of Libya on October 26, 2007, as the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite took this picture. While plumes in the west are beige, reminiscent of the Sahara's sands, the plumes in the east are distinctly darker. The differences in color can be traced to the plumes's varied origins.

  9. Nickel refinery dust

    Integrated Risk Information System (IRIS)

    Nickel refinery dust ; no CASRN Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  10. Dust Obscures Korea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The dust cloud over eastern Asia was so thick on March 21, 2002, that the Korean Peninsula completely disappeared from view in this Sea-viewing Wide Field-of-view Sensor (SeaWiFS) image of the region. Parts of South Korea report that visibility at the surface is less than 50 m (165 feet). Airports throughout the region canceled flights due to the poor visibility. Eyewitnesses in China report that the dust was so thick in Beijing at times that visibility was limited to 100 m (330 feet), while in parts of the Gansu Province visibility was reported at less than 10 m (33 feet). Chinese officials say this is the worst dust storm to hit in more than 10 years. Dust from an earlier event still colors the air to the east of Japan. (The island of Honshu is just peeking out from under the cloud cover in these images.) Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  11. Dust Devil Dynamics

    NASA Astrophysics Data System (ADS)

    Correa, C. E.; Escarguel, A.; Horton, W.; Arnas, C.; Couedel, L.; Benkadda, S.

    2013-12-01

    A self-consistent hydrodynamic model for the onset of a dust devil vortex is derived and analyzed. The horizontal toroidal flow and vertical velocity field are driven by the vertical temperature gradient instability of gravity waves. The critical temperature gradient is derived and the associated eigenmodes for simple models are given. The nonlinear dynamics in the vertical/horizontal flows drive the toroidal flow through a parametric decay process. Methods developed for triboelectric charging of dust are used to compute the electric polarization vector from the charging of the sand particles. Elementary comparisons are made with the data from dust devil observations and research and simulations by Farrell et al. 2004, 2006. The parameters for a proposed Dust Devil laboratory experiment at Aix-Marseille University are presented. Following R. L. Miller et al. JGR 2006 estimates are made of the overall contribution to the mid-latitude aerosol layer in the atmosphere that acts to moderate global climate temperature increases through a negative feedback loop. The problem has an analog in terms of the heating of the boron or beryllium coated steel vacuum vessel walls in tokamaks where the core plasma plays the role of the sun and has a temperature (~ 10keV ) that exceeds that of the core of the sun.

  12. Stellar Ontogeny: From Dust...

    ERIC Educational Resources Information Center

    MOSAIC, 1978

    1978-01-01

    Discusses the process of star formation. Infrared and radio astronomy, particularly microwave astronomy is used to provide information on different stages of stellar formation. The role of dust and gas which swirl through the interstellar regions of a galaxy and the collapse of a cloud in star formation are also presented. (HM)

  13. Dust devil dynamics

    NASA Astrophysics Data System (ADS)

    Horton, W.; Miura, H.; Onishchenko, O.; Couedel, L.; Arnas, C.; Escarguel, A.; Benkadda, S.; Fedun, V.

    2016-06-01

    A self-consistent hydrodynamic model for the solar heating-driven onset of a dust devil vortex is derived and analyzed. The toroidal flows and vertical velocity fields are driven by an instability that arises from the inversion of the mass density stratification produced by solar heating of the sandy surface soil. The nonlinear dynamics in the primary temperature gradient-driven vertical airflows drives a secondary toroidal vortex flow through a parametric interaction in the nonlinear structures. While an external tangential shear flow may initiate energy transfer to the toroidal vortex flow, the nonlinear interactions dominate the transfer of vertical-radial flows into a fast toroidal flow. This secondary flow has a vertical vorticity, while the primary thermal gradient-driven flow produces the toroidal vorticity. Simulations for the complex nonlinear structure are carried out with the passive convection of sand as test particles. Triboelectric charging modeling of the dust is used to estimate the charging of the sand particles. Parameters for a Dust Devil laboratory experiment are proposed considering various working gases and dust particle parameters. The nonlinear dynamics of the toroidal flow driven by the temperature gradient is of generic interest for both neutral gases and plasmas.

  14. Collection of cometary dust

    NASA Astrophysics Data System (ADS)

    Lell, P.; Igenbergs, E.; Kuczera, H.; Pailer, N.

    Rendezvous Missions to Comets lead to low velocities at the nucleus of the comet. The resulting impact velocity of the cometary dust on a target will range between 10 and 400 m/s. The dust particle which impacts on a target can be collected for a subsequent in-situ analysis. The collection efficiency of a target depends in addition to obvious geometrical conditions upon the surface of the target. The surface characteristics can be divided into two groups: ``dirty'' surfaces, covered with silicate or hydrocarbon compounds (for example vacuum grease), ``clean'' surfaces, like gold (with additional sputtering). This paper deals with the experimental and theoretical investigation of the collection efficiency of ``clean'' targets. Laboratory experiments are described which were conducted at the Technische Universität München, Lehrstuhl für Raumfahrttechnik, and the Max-Planck-Institut für Kernphysik, Heidelberg. In both experiments an electromagnetic accelerator is used to accelerate different types of dust in vacuum to velocities between 10 and 400 m/s. The target is then examined under the microscope and a secondary ion mass spectrometer (which is a model of the laboratory carried on board of the spacecraft for ``in situ'' analysis). The adhesion of the dust grains at the target is evaluated experimentally in an ultracentrifuge.

  15. Dust That's Worth Keeping

    SciTech Connect

    Hazi, A

    2006-01-25

    Images taken of interstellar space often display a colorful canvas of portions of the electromagnetic spectrum. Dispersed throughout the images are interstellar clouds of dust and gas--remnants ejected from stars and supernovae over billions and billions of years. For more than 40 years, astronomers have observed that interstellar dust exhibits a consistent effect at a spectral wavelength of 2,175 angstroms, the equivalent of 5.7 electronvolts in energy on the electromagnetic spectrum. At this wavelength, light from stars is absorbed by dust in the interstellar medium, blocking the stars light from reaching Earth. The 2,175-angstrom feature, which looks like a bump on spectra, is the strongest ultraviolet-visible light spectral signature of interstellar dust and is visible along nearly every observational line of sight. Scientists have sought to solve the mystery of what causes the 2,175-angstrom feature by reproducing the effect in the laboratory. They speculated a number of possibilities, including fullerenes (buckyballs), nanodiamonds, and even interstellar organisms. However, none of these materials fits the data for the unique spectral feature. Limitations in the energy and spatial resolution achievable with electron microscopes and ion microprobes--the two main instruments used to study samples of dust--have also prevented scientists from finding the answer. A collaborative effort led by Livermore physicist John Bradley and funded by the National Aeronautics and Space Administration (NASA) has used a new-generation transmission electron microscope (TEM) and nanoscale ion microprobe to unlock the mystery. The Livermore group includes physicists Zu Rong Dai, Ian Hutcheon, Peter Weber, and Sasa Bajt and postdoctoral researchers Hope Ishii, Giles Graham, and Julie Smith. They collaborated with the University of California at Davis (UCD), Lawrence Berkeley National Laboratory, Washington University's Laboratory for Space Sciences in St. Louis, and NASA's Ames

  16. Dust That's Worth Keeping

    NASA Technical Reports Server (NTRS)

    Hazi, A.

    2006-01-01

    Images taken of interstellar space often display a colorful canvas of portions of the electromagnetic spectrum. Dispersed throughout the images are interstellar clouds of dust and gas--remnants ejected from stars and supernovae over billions and billions of years. For more than 40 years, astronomers have observed that interstellar dust exhibits a consistent effect at a spectral wavelength of 2,175 angstroms, the equivalent of 5.7 electronvolts in energy on the electromagnetic spectrum. At this wavelength, light from stars is absorbed by dust in the interstellar medium, blocking the stars light from reaching Earth. The 2,175-angstrom feature, which looks like a bump on spectra, is the strongest ultraviolet-visible light spectral signature of interstellar dust and is visible along nearly every observational line of sight. Scientists have sought to solve the mystery of what causes the 2,175-angstrom feature by reproducing the effect in the laboratory. They speculated a number of possibilities, including fullerenes (buckyballs), nanodiamonds, and even interstellar organisms. However, none of these materials fits the data for the unique spectral feature. Limitations in the energy and spatial resolution achievable with electron microscopes and ion microprobes--the two main instruments used to study samples of dust--have also prevented scientists from finding the answer. A collaborative effort led by Livermore physicist John Bradley and funded by the National Aeronautics and Space Administration (NASA) has used a new-generation transmission electron microscope (TEM) and nanoscale ion microprobe to unlock the mystery. The Livermore group includes physicists Zu Rong Dai, Ian Hutcheon, Peter Weber, and Sasa Bajt and postdoctoral researchers Hope Ishii, Giles Graham, and Julie Smith. They collaborated with the University of California at Davis (UCD), Lawrence Berkeley National Laboratory, Washington University's Laboratory for Space Sciences in St. Louis, and NASA's Ames

  17. Jumbo tornado outbreak of 3 April 1974

    NASA Technical Reports Server (NTRS)

    Fujita, T. T.

    1974-01-01

    General meteorological data concerning the Jumbo tornado outbreak are presented. In terms of tornado number and total path mileage, it was more extensive than all known outbreaks. Most of the intense tornadoes avoided the large cities, however. Turn information is analyzed in detail. Left-turn tornadoes were more intense than right-turn tornadoes. Many important phenomena were observed, such as multiple suction vortices, family tornadoes, and cousin tornadoes spawned from interacting tornado cyclones. Aerial survey data will aid greatly in the solution of various scales of rotating motions, leading to improved prediction and warning of tornadoes.

  18. Data modeling for detection of epidemic outbreak

    NASA Astrophysics Data System (ADS)

    Jaenisch, Holger M.; Handley, James W.; Jaenisch, Kristina L.; Conn, Michael S.; Faucheux, Jeffrey P.

    2005-05-01

    Data Modeling is successfully applied to outbreak detection using epidemicological time series data. With proper selection of features, same day detection was demonstrated. Predictive Data Models are derived from the features in the form of integro-differential equations or their solution. These models are used as real-time change detectors. Data Modeling enables change detection using only nominal (no-outbreak) examples for training. Modeling naturally occurring dynamics due to assignable causes such as flu season enables distinction to be made of chemical and biological (chem-bio) causes.

  19. WKB calculation of an epidemic outbreak distribution

    NASA Astrophysics Data System (ADS)

    Black, Andrew J.; McKane, Alan J.

    2011-12-01

    We calculate both the exponential and prefactor contributions in a WKB approximation of the master equation for a stochastic SIR model with highly oscillatory dynamics. Fixing the basic parameters of the model, we investigate how the outbreak distribution changes with the population size. We show that this distribution rapidly becomes highly non-Gaussian, acquiring large tails, indicating the presence of rare but large outbreaks, as the population is made smaller. The analytic results are found to be in excellent agreement with simulations until the systems become so small that the dynamics are dominated by fade-out of the disease.

  20. Protection of SAAO observing site against light and dust pollution

    NASA Astrophysics Data System (ADS)

    Sefako, Ramotholo; Vaisanen, Petri

    2015-08-01

    South African Astronomical Observatory (SAAO) observing station near Sutherland, Northern Cape, is one of the darkest sites for optical and IR astronomy in the world. The SAAO hosts and operates several optical and IR telescopes, including the Southern African Large Telescope (SALT) and a number of international robotic telescopes, most of which were attracted by the good night sky conditions for optical astronomy at SAAO. To ensure that the conditions remain optimal for astronomy and our night skies are protected against light and dust pollution, a legislation called the Astronomy Geographic Advantage (AGA) Act, of 2007, was enacted. The Act empowers the South African minister of Science and Technology to regulate things that could pose a threat to both radio and/or optical astronomy in areas that are declared Astronomy Advantage Areas (or AAAs) in South Africa. For optical astronomy, the main challenges are those that are likely to be posed by light and dust pollution as result of wind energy developments, and petroleum gas and oil exploration and exploitation in the area. We give an update and current status of possible threats to the quality of the night skies at SAAO and the challenges relating to the AGA Act implementation and enforcement. We discuss measures that are put in place to protect the Observatory, including relevant studies using a planned wind energy facility to quantify the severity of the threats posed by light pollution from these and similar facilities.

  1. Transpacific transport of mineral dust: Its impact in the United States and on sulfate, nitrate, and ozone in Asian pollution plumes

    NASA Astrophysics Data System (ADS)

    Fairlie, Thomas Duncan

    This thesis examines the transpacific transport of mineral dust from Asia, its impact on aerosol concentrations in the United States, and on nitrate, sulfate, and ozone in Asian pollution plumes. We use observations from ground stations, aircraft, and satellite platforms, interpreted using a global three-dimensional chemical transport model (GEOS-Chem) in which we have represented dust mobilization, transport, and deposition. We find that the best simulation of North American surface observations is achieved when we restrict dust sources to year-round arid areas, but include a significant wind threshold for mobilization. The model captures the seasonal cycle in surface dust concentrations over the northern Pacific, the outflow of dust from Asia in the free troposphere, and the timing and distribution of Asian dust outbreaks in the United States in spring 2001. We find that Asian dust persists in surface air in western states beyond these sudden spring outbreaks, and accounts for 40% of the worst visibility days due to dust in the West in 2001. Thus, state governments need to account for transpacific dust in setting attainable visibility goals. We have also represented the uptake of acid gases SO2, H 2SO4, and HNO3 on dust in the model, and used it to interpret aircraft observations of nitrate and sulfate partitioning in transpacific dust plumes during April-May 2006. The observations show that particulate nitrate was primarily associated with the dust, sulfate was primarily associated with ammonium, and that Asian dust remained alkaline across the Pacific. To reproduce this in the model requires that uptake of HNO3 and SO2 on dust is much weaker than assumed in previous model studies. The model overestimates gas-phase HNO3 by a factor of 2-3, typical of other models; we demonstrate that this cannot be corrected by uptake on dust. Dust remains alkaline in the model because the uptake of acid gases is slow relative to the lifetime of dust against deposition. This

  2. Two Outbreaks of Occupationally Acquired Histoplasmosis: More than Workers at Risk

    PubMed Central

    Huhn, Gregory D.; Austin, Connie; Carr, Mark; Heyer, Diana; Boudreau, Pam; Gilbert, Glynnis; Eimen, Terry; Lindsley, Mark D.; Cali, Salvatore; Conover, Craig S.; Dworkin, Mark S.

    2005-01-01

    Objective: The objective of this study was to determine the etiology and risk factors for acute histoplasmosis in two outbreaks in Illinois among laborers at a landfill in 2001 and at a bridge reconstruction site in 2003. Design: We performed environmental investigations during both outbreaks and also performed an analytic cohort study among bridge workers. Participants: Workers at the landfill during May 2001 and those at the bridge site during August 2003 participated in the study. At the landfill, workers moved topsoil from an area that previously housed a barn; at the bridge, workers observed bat guano on bridge beams. Evaluations/Measurements: We defined a case by positive immunodiffusion serology, a ≥ 4-fold titer rise in complement fixation between acute and convalescent sera, or positive urinary Histoplasma capsulatum (HC) antigen. Relative risks (RR) for disease among bridge workers were calculated using bivariate analysis. Results: Eight of 11 landfill workers (73%) and 6 of 12 bridge workers (50%) were laboratory-confirmed histoplasmosis cases. Three bridge workers had positive urinary HC antigen. At the bridge, seeing or having contact with bats [RR = 7.0; 95% confidence interval (CI), 1.1–43.0], jack-hammering (RR = 4.0; 95% CI, 1.2–13.3), and waste disposal (RR = 4.0; 95% CI, 1.2–13.3) were the most significant job-related risk factors for acquiring histoplasmosis. Conclusions: Workers performing activities that aerosolized topsoil and dust were at increased risk for acquiring histoplasmosis. Relevance to Professional and Clinical Practice: Employees should wear personal protective equipment and use dust-suppression techniques when working in areas potentially contaminated with bird or bat droppings. Urinary HC antigen testing was important in rapidly identifying disease in the 2003 outbreak. PMID:15866767

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

    NASA Astrophysics Data System (ADS)

    Jish Prakash, P.; Stenchikov, G.; Kalenderski, S.; Osipov, S.; Bangalath, H.

    2014-07-01

    Located in the dust belt, the Arabian Peninsula is a major source of atmospheric dust. Frequent dust outbreaks and some 15 to 20 dust storms per year have profound effects on all aspects of human activity and natural processes in this region. To quantify the effect of severe dust events on radiation fluxes and regional climate characteristics, we simulated the storm that occurred on 18-20 March 2012 using a regional weather research forecast model fully coupled with the chemistry/aerosol module (WRF-Chem). This storm swept over a remarkably large area affecting the entire Middle East, North-Eastern Africa, Afghanistan and Pakistan. It was caused by a southward propagating cold front and associated winds activated the dust production in river valleys of the lower Tigris and Euphrates in Iraq, the coastal areas in Kuwait, Iran, and the United Arab Emirates, Rub al Khali, An Nafud and Ad Dahna deserts, and along the Red Sea coast on the west side of the Arabian Peninsula. Our simulation results compare well with available ground-based and satellite observations. The total amount of dust generated by the storm reached 93.76 Mt. About 80% of this amount deposited within the calculation domain. The Arabian Sea and Persian Gulf received 5.3 Mt, and the Red Sea 1.2 Mt. Dust particles bring nutrients to marine ecosystems, which is especially important for the oligothrophic Northern Red Sea. However, their contribution to the nutrient balance in the Red Sea remains largely unknown. By scaling the effect of one storm to the number of dust storms observed annually over the Red Sea, we roughly estimate the annual dust deposition to the Red Sea to be 6 Mt.

  4. Reuyl Crater Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 13 May 2002) The Science The rugged, arcuate rim of the 90 km crater Reuyl dominates this THEMIS image. Reuyl crater is at the southern edge of a region known to be blanketed in thick dust based on its high albedo (brightness) and low thermal inertia values. This thick mantle of dust creates the appearance of snow covered mountains in the image. Like snow accumulation on Earth, Martian dust can become so thick that it eventually slides down the face of steep slopes, creating runaway avalanches of dust. In the center of this image about 1/3 of the way down is evidence of this phenomenon. A few dozen dark streaks can be seen on the bright, sunlit slopes of the crater rim. The narrow streaks extend downslope following the local topography in a manner very similar to snow avalanches on Earth. But unlike their terrestrial counterparts, no accumulation occurs at the bottom. The dust particles are so small that they are easily launched into the thin atmosphere where they remain suspended and ultimately blow away. The apparent darkness of the avalanche scars is due to the presence of relatively dark underlying material that becomes exposed following the passage of the avalanche. Over time, new dust deposition occurs, brightening the scars until they fade into the background. Although dark slope streaks had been observed in Viking mission images, a clear understanding of this dynamic phenomenon wasn't possible until the much higher resolution images from the Mars Global Surveyor MOC camera revealed the details. MOC images also showed that new avalanches have occurred during the time MGS has been in orbit. THEMIS images will allow additional mapping of their distribution and frequency, contributing new insights about Martian dust avalanches. The Story The stiff peaks in this image might remind you of the Alps here on Earth, but they really outline the choppy edge of a large Martian crater over 50 miles wide (seen in the context image at right). While these aren

  5. Grain-size signature of Saharan dust over the Atlantic Ocean at 12°N

    NASA Astrophysics Data System (ADS)

    van der Does, Michelle; Korte, Laura; Munday, Chris; Brummer, Geert-Jan; Stuut, Jan-Berend

    2015-04-01

    Every year, an estimated 200 million tons of Saharan dust are deposited in the Atlantic Ocean. On its way from source to sink, the dust can be influenced by many climatic processes, but it also affects climate itself in various ways that are far from understood. In order to constrain the relations between atmospheric dust and climate, we deployed ten submarine sediment traps along a transect in the Atlantic Ocean at 12˚N, at 1200m and 3500m water depth. These have been sampling Saharan dust settling in the ocean since October 2012. Samples of seven of these sediment traps have been successfully recovered during RV Pelagia cruise 64PE378 in November 2013. The transect also includes three floating dust collectors and two on-land dust collectors, and all the instruments lie directly underneath the largest dust plume originating from the African continent. This study focuses on the size of the dust particles, which can have an effect on the positive or negative radiation balance in the atmosphere. Small particles in the high atmosphere can reflect incoming radiation and therefore have a cooling effect on climate. Large particles in the lower atmosphere have the opposite effect by absorbing reflected radiation from the Earth's surface. Mineral dust also affects carbon export to the deep ocean by providing mineral ballast for organic particles, and the size of the dust particles directly relates to the downward transport velocity. Here I will present the measured grain-size distributions of samples from seven sediment traps recovered from the 12°N-latitude transect. The data show seasonal variations, with finer grained dust particles during winter and spring, and coarser grained particles during summer and fall. Samples from multiple years should give more details about the dust's seasonality. Also a fining trend of the grain sizes of the dust particles from source (Africa) to sink (Caribbean) is observed, which is also expected due to intuitive relationships between

  6. Saharan Dust Aerosol Radiative Forcing Measured from Space.

    NASA Astrophysics Data System (ADS)

    Li, F.; Vogelmann, A. M.; Ramanathan, V.

    2004-07-01

    This study uses data collected from the Clouds and the Earth's Radiant Energy System (CERES) and the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments to determine Saharan dust broadband shortwave aerosol radiative forcing over the Atlantic Ocean near the African coast (15° 25°N, 45° 15°W). The clear-sky aerosol forcing is derived directly from these data, without requiring detailed information about the aerosol properties that are not routinely observed such as chemical composition, microphysical properties, and their height variations. To determine the diurnally averaged Saharan dust radiative forcing efficiency (i.e., broadband shortwave forcing per unit optical depth at 550 nm, W m-2 τ-1a), two extreme seasons are juxtaposed: the high-dust months [June August (JJA)] and the low-dust months [November January (NDJ)]. It is found that the top-of-atmosphere (TOA) diurnal mean forcing efficiency is -35 ± 3 W m-2 τ-1a for JJA, and -26 ± 3 W m-2 τ-1a for NDJ. These efficiencies can be fit by reducing the spectrally varying aerosol single-scattering albedo such that its value at 550 nm is reduced from 0.95 ± 0.04 for JJA to about 0.86 ± 0.04 for NDJ. The lower value for the low-dust months might be influenced by biomass-burning aerosols that were transported into the study region from equatorial Africa. Although the high-dust season has a greater (absolute value of the) TOA forcing efficiency, the low-dust season may have a greater surface forcing efficiency. Extrapolations based on model calculations suggest the surface forcing efficiencies to be about -65 W m-2 τ-1a for the high-dust season versus -81 W m-2 τ-1a for the low-dust season. These observations indicate that the aerosol character within a region can be readily modified, even immediately adjacent to a powerful source region such as the Sahara. This study provides important observational constraints for models of dust radiative forcing.


  7. Global dust model intercomparison in AeroCom phase I

    SciTech Connect

    Huneeus, N.; Schulz, M.; Balkanski, Y.; Griesfeller, J.; Prospero, J.; Kinne, S.; Bauer, S.; Boucher, O.; Chin, M.; Dentener, F.; Diehl, T.; Easter, R.; Fillmore, D.; Ghan, S.; Ginoux, P.; Grini, A.; Horowitz, L.; Koch, D.; Krol, M. C.; Landing, W.; Liu, X.; Mahowald, N.; Miller, R.; Morcrette, J. -J.; Myhre, G.; Penner, J.; Perlwitz, J.; Stier, P.; Takemura, T.; Zender, C. S.

    2011-08-01

    This study presents the results of a broad intercomparison of a total of 15 global aerosol models within the AeroCom project. Each model is compared to observations related to desert dust aerosols, their direct radiative effect, and their impact on the biogeochemical cycle, i.e., aerosol optical depth (AOD) and dust deposition. Additional comparisons to Angström exponent (AE), coarse mode AOD and dust surface concentrations are included to extend the assessment of model performance and to identify common biases present in models. These data comprise a benchmark dataset that is proposed for model inspection and future dust model development. There are large differences among the global models that simulate the dust cycle and its impact on climate. In general, models simulate the climatology of vertically integrated parameters (AOD and AE) within a factor of two whereas the total deposition and surface concentration are reproduced within a factor of 10. In addition, smaller mean normalized bias and root mean square errors are obtained for the climatology of AOD and AE than for total deposition and surface concentration. Characteristics of the datasets used and their uncertainties may influence these differences. Large uncertainties still exist with respect to the deposition fluxes in the southern oceans. Further measurements and model studies are necessary to assess the general model performance to reproduce dust deposition in ocean regions sensible to iron contributions. Models overestimate the wet deposition in regions dominated by dry deposition. They generally simulate more realistic surface concentration at stations downwind of the main sources than at remote ones. Most models simulate the gradient in AOD and AE between the different dusty regions. However the seasonality and magnitude of both variables is better simulated at African stations than Middle East ones. The models simulate the offshore transport of West Africa throughout the year but they

  8. 16 Extraordinary African Americans.

    ERIC Educational Resources Information Center

    Lobb, Nancy

    This collection for children tells the stories of 16 African Americans who helped make America what it is today. African Americans can take pride in the heritage of these contributors to society. Biographies are given for the following: (1) Sojourner Truth, preacher and abolitionist; (2) Frederick Douglass, abolitionist; (3) Harriet Tubman, leader…

  9. African Studies Computer Resources.

    ERIC Educational Resources Information Center

    Kuntz, Patricia S.

    African studies computer resources that are readily available in the United States with linkages to Africa are described, highlighting those most directly corresponding to African content. Africanists can use the following four fundamental computer systems: (1) Internet/Bitnet; (2) Fidonet; (3) Usenet; and (4) dial-up bulletin board services. The…

  10. African Literature as Celebration.

    ERIC Educational Resources Information Center

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  11. Educating African American Males

    ERIC Educational Resources Information Center

    Bell, Edward E.

    2010-01-01

    Background: Schools across America spend money, invest in programs, and sponsor workshops, offer teacher incentives, raise accountability standards, and even evoke the name of Obama in efforts to raise the academic achievement of African American males. Incarceration and college retention rates point to a dismal plight for many African American…

  12. Africans Away from Home.

    ERIC Educational Resources Information Center

    Clarke, John Henrik

    Africans who were brought across the Atlantic as slaves never fully adjusted to slavery or accepted its inevitability. Resistance began on board the slave ships, where many jumped overboard or committed suicide. African slaves in South America led the first revolts against tyranny in the New World. The first slave revolt in the Caribbean occurred…

  13. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  14. Geochemical and isotopic characterization of the Bodélé Depression dust source and implications for transatlantic dust transport to the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Abouchami, Wafa; Näthe, Kerstin; Kumar, Ashwini; Galer, Stephen J. G.; Jochum, Klaus Peter; Williams, Earle; Horbe, Adriana M. C.; Rosa, João W. C.; Balsam, William; Adams, David; Mezger, Klaus; Andreae, Meinrat O.

    2013-10-01

    The Bodélé Depression (Chad) in the central Sahara/Sahel region of Northern Africa is the most important source of mineral dust to the atmosphere globally. The Bodélé Depression is purportedly the largest source of Saharan dust reaching the Amazon Basin by transatlantic transport. Here, we have undertaken a comprehensive study of surface sediments from the Bodélé Depression and dust deposits (Chad, Niger) in order to characterize geochemically and isotopically (Sr, Nd and Pb isotopes) this dust source, and evaluate its importance in present and past African dust records. We similarly analyzed sedimentary deposits from the Amazonian lowlands in order to assess postulated accumulation of African mineral dust in the Amazon Basin, as well as its possible impact in fertilizing the Amazon rainforest. Our results identify distinct sources of different ages and provenance in the Bodélé Depression versus the Amazon Basin, effectively ruling out an origin for the Amazonian deposits, such as the Belterra Clay Layer, by long-term deposition of Bodélé Depression material. Similarly, no evidence for contributions from other potential source areas is provided by existing isotope data (Sr, Nd) on Saharan dusts. Instead, the composition of these Amazonian deposits is entirely consistent with derivation from in-situ weathering and erosion of the Precambrian Amazonian craton, with little, if any, Andean contribution. In the Amazon Basin, the mass accumulation rate of eolian dust is only around one-third of the vertical erosion rate in shield areas, suggesting that Saharan dust is "consumed" by tropical weathering, contributing nutrients and stimulating plant growth, but never accumulates as such in the Amazon Basin. The chemical and isotope compositions found in the Bodélé Depression are varied at the local scale, and have contrasting signatures in the "silica-rich" dry lake-bed sediments and in the "calcium-rich" mixed diatomites and surrounding sand mat