DOCSLIB.ORG

Shankar Chellam, University of Houston (Currently at Texas A&M)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Shankar Chellam, University of Houston (Currently at Texas A&M) TO: Texas Air Research Center FROM: Shankar Chellam, University of Houston (currently at Texas A&M) SUBJECT: Final Report PROJECT NUMBER: 413UHH0143A PROJECT TITLE: Detailed elemental characterization of Saharan dust to quantify its contributions to PM2.5 and PM10 during episodic intrusions in Houston PROJECT PERIOD: September 1, 2013 – July 15, 2015 DATE: November 7, 2015 BACKGROUND The arid regions of North Africa are the world’s largest contributor of dust, estimated to emit about 800 Tgy-1 of soil dust annually. This North African particulate matter (PM) is transported across the Atlantic Ocean to the southern continental United States increasing the ambient PM10 and PM2.5 burden in Texas typically during the summer and early fall seasons. It is emphasized that isolating air pollutant contributions is difficult in complex urban environments. Also, the ability of detailed chemical speciation to differentiate sources is challenged because of the existence of myriad local sources. Another important source in Texas is primary emissions from motor vehicles. According to the United States Department of Transportation’s Federal Highway Administration, the State of Texas ranks second only to California in terms of vehicle miles traveled, with nearly 19 billion miles driven in November 2011 alone. Realistic estimates of tailpipe and non-tailpipe particulate emissions under actual on-road conditions incorporating several real-world sources of variability including maintenance histories, vehicle age, engine size and type, driving habits, and season can be obtained from measurements in roadway tunnels. We are interested in developing methods to quantify long-range transported PM as well as those locally emitted from motor vehicles. This report briefly summarizes our findings and the reader is referred to our peer- reviewed publications listed at the end for more detailed information. OBJECTIVES The objectives of the research completed during this period were to: Accurately measure major and trace elements in different mineral dust sources and in ambient PM in receptor locations to quantitatively estimate contributions of long-range dust and locally entrained crustal material and local anthropogenic sources. Comprehensively characterize wide suite of elements in PM2.5 and PM10 emitted from light duty vehicles (LDVs) traversing a tunnel with emphasis on Rh, Pd, and Pt and develop a novel LDV source profile by including platinum group elements. METHODOLOGY For accurate source apportionment, we developed a representative source profile of aerosols originating in North Africa by collecting samples in a remote location in the Caribbean (Barbados) during dust episodes before they entered the continental United States. Daily PM2.5 and PM10 were also collected at Clinton Drive and Channelview using R&P 2025 samplers. African dust passing over Barbados were collected at Ragged Point, which is a field station on the east coast of Barbados. Two sets of PM2.5 and PM10 samples were also collected from inside the Washburn Tunnel. PM samples were acid-digested in two steps in Teflon-lined vessels (HP-500 Plus) using a microwave (MARS 5, CEM Corp.). Fifteen main group elements (Na, Mg, Al, Si, K, Ca, Ga, As, Se, Rb, Sr, Sn, Sb, Ba, Pb), 14 transition metals (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Cd, W) and 14 lanthanoids (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) were quantified by dynamic reaction cell – quadrupole – ICP-MS (ELAN DRCII, PerkinElmer). For platinum group metals, aqua regia was used first before the above-described method was implemented. RESULTS AND DISCUSSION Figure 1. Back trajectories demonstrating the North African origin of dust during July 25, 26, and 27 in Houston. Several lines of evidence pointed that the air mass originated in North Africa and moved across the tropical Atlantic and entered the Western Gulf of Mexico, impacting air quality over the Houston area on 25-27 July, 2008. Figure 1 is one such example that depicts NOAA HYSPLIT back trajectories. Electron micrographs and energy dispersive X-ray spectroscopy of aerosol samples from Barbados collected during Saharan dust outbreaks revealed similar morphology, size distribution, and elemental characteristics to long-range transported North African dust collected in Europe. Figure 2. Representative energy dispersive X‐ray spectrum of Saharan dust. In this project, we demonstrated that chemical mass balancing can successfully isolate, differentiate and quantify the relative contributions from local and global mineral dust sources through detailed measurements of a wide suite of elements in ambient PM. We identified a major dust storm originating in Northwest Africa in mid-July 2008 which eventually impacted air quality in Houston during July 25, 26, and 27, 2008. Daily PM2.5 and PM10 samples were collected at two sites in Houston over a 2-week period encompassing the Saharan dust episode to quantify the transported mineral dust concentrations during this peak event. Average PM concentrations more than doubled during the Saharan intrusion compared with non-Saharan. Relative concentrations of several elements often associated with anthropogenic sources were significantly diluted by crustal minerals coincident with the large-scale Saharan dust intrusion. During non- Saharan days, local mineral dust sources including cement manufacturing, and soil and road dust contributed in total 26% to PM2.5 mass and 50% to PM10 mass; during the three-day Saharan episode the total dust contribution increased to 64% for PM2.5 and 85% for PM10. Importantly, this approach was also able to determine that local emissions of crustal minerals dominated the period immediately following the Saharan dust episode: simple quantification of bulk crustal materials may have misappropriated this elevated PM to trans-Atlantic transport of Saharan dust. During this time period, we also completed publications and presentations related to measurement of platinum group metals in tunnel PM to develop a unique source profile for on-road light duty vehicles. Average source profile abundances were derived by subtracting ventilation air concentrations from those measured in the tunnel and dividing by the elevation in PM mass concentrations. Total tailpipe and non-tailpipe LDV PM emissions were dominated by crustal species such as Ca, Si, Fe, Al, Mg, K, and Ti (0.23 for Ti to 15.3% for Ca in PM10 and 0.26 for Ti to 8.6% for Ca in PM2.5). These elements exhibited a strong preference to the coarse size mode and had enrichment factors close to unity, indicating that they largely originated from the crustal mineral component of road dust. However, their abundances in tunnel PM differed from upper continental crust values reflecting small but significant contributions from light duty vehicles, which was nevertheless overshadowed by crustal material resuspension in the tunnel. Of all these crustal elements, only Fe had a higher contribution to PM2.5 (5.8%) compared with PM10 (3.4%) indicative of non-mineral sources including engine and brake wear. Anthropogenic elements such as Ba, Zn, Zr, Cu, Sn, Sb, Ga, and Pb that are well- known to be emitted by mobile sources were also prominent in the derived light duty vehicles source profiles of PM2.5 derived from the tunnel (0.01 to 0.56%) and PM10 (0.01 to 0.24%). These elements were 3.2 (Zr in PM10) to 2,025 (Sb in PM2.5) times more abundant than their UCC values corresponding to their high enrichment factors. Zn and Pb in PM2.5 accounted for only 15 and 19% of their respective PM10 levels, indicating that their major source is mechanical resuspension of enriched road dust within the tunnel. Cu, Ga, Zr, Mo, Cd, Sn, Sb, Ba, and W in PM2.5 constituted a higher fraction of PM10 (34% for Zr to 68% for Mo) indicating a greater influence from direct LDV emissions (tailpipe exhaust and brake/tire wear). PGE abundances were 493 (Pt in PM10) to 24,141 (Rh in PM2.5) times their UCC values leading to extremely high enrichment factors (890-36,575) as reported above. Their PM2.5 abundances constituted 36-60% of PM10 levels suggesting substantial tailpipe emissions of PGEs confirming their applicability as unique LDV tracers. LIST OF PUBLICATIONS AND PRESENTATIONS 1. Bozlaker, A., J.M. Prospero, M.P. Fraser, and S. Chellam (2013). Quantifying the Contribution of Long-Range Saharan Dust Transport on Particulate Matter Concentrations in Houston, Texas, using Detailed Elemental Analysis. Environmental Science and Technology, 47 10179-10187. 2. Bozlaker, A., N.J. Spada, M.P. Fraser, and S. Chellam (2014). Elemental Characterization of PM2.5 and PM10 Emitted from Light Duty Vehicles in the Washburn Tunnel of Houston, Texas: Release of Rhodium, Palladium, and Platinum. Environmental Science and Technology, 48 (1) 54-62. This paper is the most downloaded article from ES&T in the January – June 2014 period and the 3rd most downloaded article over the entire year of 2014. 3. Chellam, S., N.J. Spada, and A. Bozlaker “Elemental Characterization of PM2.5 and PM10 Emitted from Light Duty Vehicles in the Washburn Tunnel of Houston, Texas: Release of Rhodium, Palladium, and Platinum,” Association of Environmental Engineering and Science Professors’ Education and Research Conference, New Haven, CT, June 13-16, 2015. 4. Chellam, S. A. Bozlaker, N.J. Spada, and M.P. Fraser “Elemental Characterization of PM2.5 and PM10 Emitted from Light Duty Vehicles in the Washburn Tunnel of Houston, Texas: Release of Rhodium, Palladium, and Platinum,” Symposium on Trace Materials in Air, Soil, and Water, Division of Environmental Chemistry, 249th ACS National meeting, Denver, Colorado, March 22-26, 2015. .
Load more

Recommended publications
  • Variability of Mineral Dust Deposition in the Western Mediterranean Basin and South-East of France
    Atmos. Chem. Phys., 16, 8749–8766, 2016 www.atmos-chem-phys.net/16/8749/2016/ doi:10.5194/acp-16-8749-2016 © Author(s) 2016. CC Attribution 3.0 License. Variability of mineral dust deposition in the western Mediterranean basin and south-east of France Julie Vincent1, Benoit Laurent1, Rémi Losno1,a, Elisabeth Bon Nguyen1, Pierre Roullet2, Stéphane Sauvage3, Servanne Chevaillier1, Patrice Coddeville3, Noura Ouboulmane1, Alcide Giorgio di Sarra4, Antonio Tovar-Sánchez5,6, Damiano Sferlazzo4, Ana Massanet6, Sylvain Triquet1, Rafael Morales Baquero7, Michel Fornier8, Cyril Coursier9, Karine Desboeufs1, François Dulac10, and Gilles Bergametti1 1Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR7583 CNRS, Université Paris Denis Diderot, Université Paris-Est Créteil, Institut Pierre-Simon Laplace, Paris, France 2Ingénierie, Conseil, Assistance technique, Recherche, Étude (ICARE Ingénierie), Paris, France 3Département Sciences de l’Atmosphère et Génie de l’Environnement (SAGE), Mines Douai, 59508, Douai, France 4Laboratory for Earth Observations and Analyses (ENEA), Santa Maria di Galeria, Italy 5Andalusian Marine Science Institute (ICMAN, CSIC), Cádiz, Spain 6Institut Mediterrani d’Estudis Avançats (IMEDEA-CSIC/UIB), Balearic Island, Spain 7Departamento Ecologia, Universitad Granada, Granada, Spain 8Mediterranean Institute of Oceanography (MIO), UMR7294 CNRS, UMR235 IRD, Université Aix-Marseille, Université du Sud Toulon-Var, Marseille, France 9Parc national des Ecrins, Le Casset, France 10Laboratoire des Sciences du Climat et de l’Environnement (LSCE), UMR 8212 CEA-CNRS-UVSQ, Institut Pierre-Simon Laplace, Gif-sur-Yvette, France apresent address: Institut de Physique du Globe de Paris (IPGP), UMR7154 CNRS, Sorbonne Paris Cité, Université Paris Denis Diderot, Paris, France Correspondence to: J. Vincent ([email protected]) Received: 25 September 2015 – Published in Atmos.
    [Show full text]
  • Atmospheric Dust on Mars: a Review
    47th International Conference on Environmental Systems ICES-2017-175 16-20 July 2017, Charleston, South Carolina Atmospheric Dust on Mars: A Review François Forget1 Laboratoire de Météorologie Dynamique (LMD/IPSL), Sorbonne Universités, UPMC Univ Paris 06, PSL Research University, Ecole Normale Supérieure, Université Paris-Saclay, Ecole Polytechnique, CNRS, Paris, France Luca Montabone2 Laboratoire de Météorologie Dynamique (LMD/IPSL), Paris, France & Space Science Institute, Boulder, CO, USA The Martian environment is characterized by airborne mineral dust extending between the surface and up to 80 km altitude. This dust plays a key role in the climate system and in the atmospheric variability. It is a significant issue for any system on the surface. The atmospheric dust content is highly variable in space and time. In the past 20 years, many investigations have been conducted to better understand the characteristics of the dust particles, their distribution and their variability. However, many unknowns remain. The occurrence of local, regional and global-scale dust storms are better documented and modeled, but they remain very difficult to predict. The vertical distribution of dust, characterized by detached layers exhibiting large diurnal and seasonal variations, remains quite enigmatic and very poorly modeled. Nomenclature Ls = Solar Longitude (°) MY = Martian year reff = Effective radius τ = Dust optical depth (or dust opacity) CDOD = Column Dust Optical Depth (i.e. τ integrated over the atmospheric column) IR = Infrared LDL = Low Dust Loading (season) HDL = High Dust Loading (season) MGS = Mars Global Surveyor (NASA spacecraft) MRO = Mars Reconnaissance Orbiter (NASA spacecraft) MEX = Mars Express (ESA spacecraft) TES = Thermal Emission Spectrometer (instrument aboard MGS) THEMIS = Thermal Emission Imaging System (instrument aboard NASA Mars Odyssey spacecraft) MCS = Mars Climate Sounder (instrument aboard MRO) PDS = Planetary Data System (NASA data archive) EDL = Entry, Descending, and Landing GCM = Global Climate Model I.
    [Show full text]
  • Cloud Icing by Mineral Dust and Impacts to Aviation Safety
    www.nature.com/scientificreports OPEN Cloud icing by mineral dust and impacts to aviation safety Slobodan Nickovic1*, Bojan Cvetkovic1, Slavko Petković1, Vassilis Amiridis2, Goran Pejanović1, Stavros Solomos2,3, Eleni Marinou2,4 & Jugoslav Nikolic1 Ice particles in high-altitude cold clouds can obstruct aircraft functioning. Over the last 20 years, there have been more than 150 recorded cases with engine power-loss and damage caused by tiny cloud ice crystals, which are difcult to detect with aircraft radars. Herein, we examine two aircraft accidents for which icing linked to convective weather conditions has been ofcially reported as the most likely reason for catastrophic consequences. We analyze whether desert mineral dust, known to be very efcient ice nuclei and present along both aircraft routes, could further augment the icing process. Using numerical simulations performed by a coupled atmosphere-dust model with an included parameterization for ice nucleation triggered by dust aerosols, we show that the predicted ice particle number sharply increases at approximate locations and times of accidents where desert dust was brought by convective circulation to the upper troposphere. We propose a new icing parameter which, unlike existing icing indices, for the frst time includes in its calculation the predicted dust concentration. This study opens up the opportunity to use integrated atmospheric-dust forecasts as warnings for ice formation enhanced by mineral dust presence. Tere have been more than 150 accidents reported by commercial airplanes 1,2 related to cloud ice impacts, such as engine power loss, blade damage, and the icing of instrument sensors. Most of these incidences have been linked to icing in the upper troposphere in the vicinity of deep summer convection systems.
    [Show full text]
  • Analysis of Dust Aerosol Retrievals Using Satellite Data in Central Asia
    Article Analysis of Dust Aerosol Retrievals Using Satellite Data in Central Asia Longlei Li * and Irina N. Sokolik School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-404-754-1177 Received: 8 June 2018; Accepted: 19 July 2018; Published: 24 July 2018 Abstract: Several long-term monitoring of aerosol datasets from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra/Aqua, Multi-angle Imaging SpectroRadiometer (MISR), Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) were used to derive the dust aerosol optical depth (DOD) in Central Asia based on the Angstrom exponent parameter and/or the particle shape. All sensors agree very well on the interannual variability of DOD. The seasonal analysis of DOD and dust occurrences identified the largest dust loading and the most frequent dust occurrence in the spring and summer, respectively. No significant trend was found during the research period in terms of both DOD and the dust occurrence. Further analysis of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) aerosol products on a case-by-case basis in most dust months of 2007 suggested that the vertical structure is varying in terms of the extension and the dust loading from one event to another, although dust particles of most episodes have similar physical characteristics (particle shape and size). Our analysis on the vertical structure of dust plumes, the layer-integrated color ratio and depolarization ratio indicates a varied climate effect (e.g., the direct radiative impact) by mineral dust, dependent on the event being observed in Central Asia.
    [Show full text]
  • Dust Variability and Land Degradation in the Sahel Variabilité De La Poussière Et Dégradation Des Sols Au Sahel
    Belgeo Revue belge de géographie 2 | 2002 Physical geography beyond the 20st century Dust variability and land degradation in the Sahel Variabilité de la poussière et dégradation des sols au Sahel Pierre Ozer Electronic version URL: http://journals.openedition.org/belgeo/16124 DOI: 10.4000/belgeo.16124 ISSN: 2294-9135 Publisher: National Committee of Geography of Belgium, Société Royale Belge de Géographie Printed version Date of publication: 30 June 2002 Number of pages: 195-210 ISSN: 1377-2368 Electronic reference Pierre Ozer, « Dust variability and land degradation in the Sahel », Belgeo [Online], 2 | 2002, Online since 01 July 2002, connection on 19 April 2019. URL : http://journals.openedition.org/belgeo/16124 ; DOI : 10.4000/belgeo.16124 This text was automatically generated on 19 April 2019. Belgeo est mis à disposition selon les termes de la licence Creative Commons Attribution 4.0 International. Dust variability and land degradation in the Sahel 1 Dust variability and land degradation in the Sahel Variabilité de la poussière et dégradation des sols au Sahel Pierre Ozer Observers and meteorologists from all analysed countries are gratefully acknowledged for their daily collection of data used in this study. I am grateful to Prof. M. Erpicum, Dr. G. Demarée and Dr. R. Morel who have led to improvements in the paper. 1 Atmospheric mineral dust originating within the Sahara and its borders has become a major feature of the West African climate over the last decades. Dust frequency has often been regarded as one of the most important manifestations of desertification, and interest in this phenomenon has increased in recent years (Pye, 1987; Goudie and Middleton, 1992; N’Tchayi et al., 1998; Ozer, 2000B).
    [Show full text]
  • Mineralogy and Physicochemical Features of Saharan Dust Wet Deposited in the Iberian Peninsula During an Extreme Red Rain Event
    Atmos. Chem. Phys., 18, 10089–10122, 2018 https://doi.org/10.5194/acp-18-10089-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Mineralogy and physicochemical features of Saharan dust wet deposited in the Iberian Peninsula during an extreme red rain event Carlos Rodriguez-Navarro, Fulvio di Lorenzo, and Kerstin Elert Dept. Mineralogy and Petrology, University of Granada, Fuentenueva s/n, 18002 Granada, Spain Correspondence: Carlos Rodriguez-Navarro ([email protected]) Received: 26 February 2018 – Discussion started: 1 March 2018 Revised: 8 June 2018 – Accepted: 15 June 2018 – Published: 16 July 2018 Abstract. The mineralogy and physicochemical features of forcing. The lack of secondary sulfates in aggregates of unal- Saharan dust particles help to identify source areas and deter- tered calcite internally mixed with clays/iron-rich nanoparti- mine their biogeochemical, radiative, and health effects, but cles shows that iron-rich nanoparticles did not form via atmo- their characterization is challenging. Using a multianalytical spheric (acid) processing but were already present in the dust approach, here we characterized with unprecedented level of source soils. Such iron-rich nanoparticles, in addition to iron- detail the mineralogy and physicochemical properties of Sa- containing clay (nano)particles, are the source of the ∼ 20 % haran dust particles massively wet deposited ( ∼ 18 g m−2/ soluble (bioavailable) iron in the studied desert dust. The following an extreme “red rain” event triggered by a north- dust particles are a potential health hazard, specifically the ern African cyclone that affected the southern Iberian Penin- abundant and potentially carcinogenic iron-containing paly- sula during 21–23 February 2017.
    [Show full text]
  • Links to View Saharan Dust Plume
    Links to view Saharan dust plume: https://weather.cod.edu/satrad/?parms=regional-gulf-truecolor-48-1-100- 1&checked=map&colorbar= https://fluid.nccs.nasa.gov/gram/du/29.7x-95.4/?region=nam https://cds-cv.nccs.nasa.gov/GMAO-V/ Messages about the Saharan Air Layer 6-23-20 Q. What is the Saharan Air Layer? A. The Saharan Air Layer is a mass of very dry, dusty air that forms over the Sahara Desert during the late spring, summer, and early fall, and moves over the tropical North Atlantic every three to five days. Saharan Air Layer outbreaks usually occupy a 2 to 2.5-mile-thick layer of the atmosphere with the base starting about 1 mile above the surface. The warmth, dryness, and strong winds associated with the Saharan Air Layer have been shown to suppress tropical cyclone formation and intensification. Saharan Air Layer activity usually ramps up in mid-June, peaks from late June to mid-August, and begins to rapidly subside after mid-August. During the peak period, individual Saharan Air Layer outbreaks reach farther to the west (as far west as Florida, Central America and even Texas) and cover vast areas of the Atlantic (sometimes as large as the lower 48 United States). Q. How does the SAL influence weather and climate? A. The Saharan Air Layer has unique properties of warmth, dry air, and strong winds that can have significant moderating impacts on tropical cyclone formation and intensification. There are three characteristics of these Saharan dust outbreaks that can affect tropical cyclones, tropical disturbances, and the general climatology of the Atlantic tropical atmosphere: Extremely Dry Air: First, The Saharan Air Layer’s dry, dusty air has about 50% less moisture than the typical tropical atmosphere.
    [Show full text]
  • Transport of Mineral Dust from Africa and Middle East to East Asia Observed with the Lidar Network (AD-Net)
    SOLA, 2019, Vol. 15, 257−261, doi:10.2151/sola.2019-046 257 Transport of Mineral Dust from Africa and Middle East to East Asia Observed with the Lidar Network (AD-Net) Nobuo Sugimoto1, Yoshitaka Jin1, Atsushi Shimizu1, Tomoaki Nishizawa1, and Keiya Yumimoto2 1National Institute for Environmental Studies, Tsukuba, Japan 2Research Institute for Applied Mechanics, Kyushu University, Fukuoka, Japan et al. 2005). We observed lifted dust layers in Korea and Japan, Abstract which were not reproduced by a regional dust transport model. We compared with global aerosol transport models and found the dust Mineral dust transported from Africa and Middle East was was transported from Africa. observed with the Asian Dust and aerosol lidar observation Net- In 2015−2016, Leibniz Institute for Tropospheric Research work (AD-Net). In March 2018, the dense Sahara dust, reported (TROPOS) conducted continuous observation with a multi-wave- by mass media as that snow in Sochi, Russia stained into orange, length Raman lidar in Dushanbe, Tajikistan (Hofer et al. 2017), was transported to Sapporo in 4 days from Sochi and observed by and they recently restarted continuous observation. That motivated the lidar. In April 2015, dust from Middle East was transported to us to study long-range-transported dust cases using recent AD-Net Nagasaki passing across the Taklamakan desert. Dust source areas data. It would be useful if we could observe the same air mass and transport paths were studied with the global aerosol transport along the transport path to study the change in characteristics of model MASINGAR mk-2 separately calculated for different dust dust.
    [Show full text]
  • Long Term Trends in African Dust Transport to the Caribbean: African Sources, Changing Climate, and Future Scenarios
    LONG TERM TRENDS IN AFRICAN DUST TRANSPORT TO THE CARIBBEAN: AFRICAN SOURCES, CHANGING CLIMATE, AND FUTURE SCENARIOS Joseph M. Prospero Rosenstiel School of Marine and Atmospheric Science University of Miami 4600 Rickenbacker Causeway, Miami, FL 33149 [email protected] Aerosol studies were begun on Barbados in 1965 and continue to this day. Over much of this record there was a strong correlation between dust concentrations in Barbados and rainfall in the Sahel-Soudano (SS) region of North Africa. In retrospect this correlation was largely driven by three distinct periods in the early record: the period of high rainfall and low dust transport in the mid-to-late 1960s; the first drought in the early 1970s; and the extremely intense drought of the early 1980s. During this period transport showed promising relationships to various climate indices: e.g., El Niño, NAO, AMO. However, since the early 1990s there have been large year- to-year changes in SS rainfall but there is no consistent relationship to dust on Barbados or between dust and common climate indices. Furthermore, over the entire record there is a strong shift in seasonal dust transport, most notably, a great increase in winter and spring transport compared to the pre-drought and early drought period. These trends seem to suggest that there have been profound long-term changes in dust emissions and transport. A possible contributing factor could be increased population and land use in the SS region. 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.
    [Show full text]
  • Multi-Sensor Observation of a Saharan Dust Outbreak Over Transylvania, Romania in April 2019
    atmosphere Article Multi-Sensor Observation of a Saharan Dust Outbreak over Transylvania, Romania in April 2019 Nicolae Ajtai, Horat, iu S, tefănie, Alexandru Mereut, ă, Andrei Radovici and Camelia Botezan * Faculty of Environmental Science and Engineering, Babes, -Bolyai University, 30 Fântânele St., 400294 Cluj-Napoca, Romania; [email protected] (N.A.); [email protected] (H.S, .); [email protected] (A.M.); [email protected] (A.R.) * Correspondence: [email protected] Received: 17 March 2020; Accepted: 8 April 2020; Published: 9 April 2020 Abstract: Mineral aerosols are considered to be the second largest source of natural aerosol, the Saharan desert being the main source of dust at global scale. Under certain meteorological conditions, Saharan dust can be transported over large parts of Europe, including Romania. The aim of this paper is to provide a complex analysis of a Saharan dust outbreak over the Transylvania region of Romania, based on the synergy of multiple ground-based and satellite sensors in order to detect the dust intrusion with a higher degree of certainty. The measurements were performed during the peak of the outbreak on April the 24th 2019, with instruments such as a Cimel sun-photometer and a multi-wavelength Raman depolarization lidar, together with an in-situ particle counter measuring at ground level. Remote sensing data from MODIS sensors on Terra and Aqua were also analyzed. Results show the presence of dust aerosol layers identified by the multi-wavelength Raman and depolarization lidar at altitudes of 2500–4000 m, and 7000 m, respectively. The measured optical and microphysical properties, together with the HYSPLIT back-trajectories, NMMB/BSC dust model, and synoptic analysis, confirm the presence of lofted Saharan dust layers over Cluj-Napoca, Romania.
    [Show full text]
  • Airborne Dust Bulletin
    WEATHER CLIMATE WATER WMO AIRBORNE DUST BULLETIN No. 5 | July 2021 WMO Sand and Dust Storm – Warning Advisory and Overview of atmospheric dust content in 2020 Assessment System (SDS-WAS) The spatial distribution of the global surface concentration The WMO Global Sand and Dust Storm Warning Advisory of mineral dust in 2020 (Figure 1) and its anomaly relative and Assessment System (SDS-WAS) is intended to provide to climatologically mean values (1981–2010) (Figure 2) were continuous and improved SDS operational forecasts as well derived based on the dust products from the Modern-Era as to facilitate international coordinated SDS research in Retrospective Analysis for Research and Applications, the earth-system science domain, fostering the seamless Version 2 (MERRA-2) (Gelaro et al., 2017), the latest forecast of SDSs, air quality and chemical weather. It is also atmospheric reanalysis version for the modern satellite expected to sustainably realize the value of SDS scientific era produced by NASA’s Global Modelling and Assimilation research in the chain of research, operational forecasts and Office (GMAO). MERRA-2 includes an online implementation services (WMO, 2020). of the Goddard Chemistry, Aerosol, Radiation, and Transport model (GOCART) integrated into the Goddard SDS-WAS is the only initiative in the world that has been Earth Observing System Model, Version 5 (GEOS-5) and providing the longest-running SDS research and operational is capable of simulating five types of aerosols. The results forecasts. After fifteen years of successful development, SDS- shown here are based on the dust surface concentration WAS looks at new scientific and operational challenges in the parameter which is different from the dust aerosol optical next five years (2021-2025) to support disaster prevention, depth (DAOD) parameter and more relevant to ground air mitigation and adaptation choices in a constantly changing quality.
    [Show full text]
  • Asian and Saharan Dust from a Chemical/Mineralogical Point of View: Differences and Similarities from Bulk and Single Particle Measurements
    E3S Web of Conferences 99, 03001 (2019) https://doi.org/10.1051/e3sconf/20199903001 CADUC 2019 Asian and Saharan dust from a chemical/mineralogical point of view: differences and similarities from bulk and single particle measurements Konrad Kandler1,* and Dirk Scheuvens1 1Institute for Applied Geosciences, Technical University Darmstadt, 64287 Darmstadt, Germany Abstract. This paper combines a review on the importance of dust composition with respect to numerous atmospheric impacts with field measurements performed in African and Central Asian dust. In the review part, the most important dust components and their relevance for certain processes are outlined. Typical compositions from bulk measurements for African and Asian dust are presented. Generally the local variation in composition can be higher than the differences between Asian and African dust and their according specific sources. While similar general results are available from individual particle analyses, these investigations add important information on mixing state and homogeneity of composition. Atmospheric aging of mineral dust is observed globally, depending on transport distances from the sources and transport environment. As an illustration, comparative field measurements of African and Asian dust deposition are presented. 1 Introduction Mineral dust in the atmosphere is also subject to chemical reactions, acts as catalyser and provides surface Mineral dust undoubtedly is one of the most important for heterogeneous reactions. For example, the carbonate aerosol types in the Earth system [1]. Dust derived from compounds in dust can lower considerably the soils is among the largest contributors to the global atmospheric acidity by reacting with nitric and sulfuric aerosol burden [2]. It dominates climate effects over acid [30, 31].
    [Show full text]