Saharan dust

CNR-ISAC, National Research Council of Italy, Institute of Atmospheric Sciences and Climate, Bologna, Italy ENEA, Roma, Italy University "G. d'Annunzio" of Chieti-Pescara, Department of Psychological, Health & Territorial Sciences, Chieti, Italy National Research Council of Italy, Institute of Atmospheric Pollution, Rende, Italy National Research Council of Italy, Institute of Dynamics for Environmental Processess, Venezia, Italy University of Urbino, Department of Pure and Applied Sciences, Urbino, Italy

We present LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies), a 3-D multi-wavelength global aerosol and cloud optical database, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. The LI-VAS database provides averaged profiles of aerosol optical properties for the potential spaceborne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global database is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent backscatter-and extinction-related Ångström exponents, derived from EAR-LINET (European Aerosol Research Lidar Network) groundbased measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversions are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO backscatter and extinction data corresponding to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud optical database based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for spaceborne lidar performance assessments. The final global data set includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data on a uniform grid of 1 • × 1 • with the original high vertical resolution of CALIPSO in order to ensure realistic Published by Copernicus Publications on behalf of the European Geosciences Union. 7128 V. Amiridis et al.: LIVAS: a 3-D multi-wavelength aerosol/cloud database simulations of the atmospheric variability in lidar end-to-end simulations. EARLINET ESA-CALIPSO database Aerosol Models from literature for size distributions and refractive index BAE at 355/532 nm Dust Poll. Dust Poll. Continental Smoke Clean Marine Clean Continental Stratospheric AERONET inversions classified based on Omar (2005) and filtered with EARLINET AERONET inversions classified based on collocation to CALIPSO aerosol types (Schuster, 2012) EAE at 355/532 nm

Vertically resolved observations of dust optical properties were carried out at the EARLINET station of Naples (southern Italy, 40.838°N, 14.183°E, 118 m above sea level) from May 2000 to August 2003. 45 outbreaks with a mean temporal length of about 4 days were observed, 40% of which were characterized by dust plume intrusion into the Planetary Boundary Layer. The mean values of the altitude of base, top and of the thickness of the dust plume were derived. Dust optical properties were studied along the vertical profile in terms of statistical and climatological analysis of aerosol backscatter, extinction and lidar ratio measured inside the dust layer. Mean values of backscattering and extinction coefficients of (1.2 ± 0.1) 10 −6 m −1 sr −1 and (0.61 ± 0.06) 10 −4 m −1 , respectively, were obtained in the whole observation period, while the mean value of LR at 351 nm resulted to be 47 ± 3 sr. Mean values of dust concentration and dust fluxes were also estimated. The highest values of concentration have been observed on spring and summer months resulting of (150 ± 60) μg•m −3 and (80 ± 30) μg•m-3 , and mean dust fluxes were (0.8 ± 0.4)•10 −3 g m −2 s −1 and (1.6 ± 0.7)•10 −3 g m −2 s −1 , respectively. Finally, aerosol optical properties retrieved from lidar vertical profiles and sun-photometer measurement, in-situ sampling and models outcomes were used to fully examine the most intense dust outbreak observed during the whole study period.

The optical properties and the spatial distribution of tropospheric aerosols layers over Naples have been studied by means of Raman lidar observations performed during Saharan dust outbreaks from May 2000 to August 2003 in the frame of the EARLINET project (Bösenberg et al., 2003). Starting from lidar profiles, the characterization of the desert dust layer in term of base, top and thickness has been performed. In order to study the mean optical properties of the aerosol and to evaluate the contribution of the dust and its variability with height a statistical approach have been followed. The optical properties of the Saharan dust layer have been studied in terms of mean values of integrated backscatter (IB), optical depth (OD) and extinction-to-backscatter ratio (LR).

h i g h l i g h t s Contribution of natural and anthropogenic PM 2.5 sources is quantified. Back-trajectories for marine and crustal sources each show input from offshore. Results for crustal source are explained by long-range transport of Saharan dust. Results for Hg species, SO 2 and NO x show influence of combustion-related plumes. Results for RGM show diurnal cycle of production characteristic of marine influence.

Background: Studies measuring health effects of Saharan dust based on large particulate matter (PM) fraction groups may be masking some effects. Long distant transport reduces the amount of heavier and larger particles in the Saharan air masses increasing the relative contribution of smaller particles that may be more innocuous. This study investigates the association between different PM fractions and daily mortality during Saharan and non-Saharan days in Barcelona, Spain. Methods: We collected daily PM 1 , PM 2.5-1 and PM 10-2.5 fractions, and cause-specific mortality (cardiovascular, respiratory and cerebrovascular) between March 2003 and December 2007. Changes of effects between Saharan and non-Saharan dust days were assessed using a time-stratified case-crossover design. Results: During non-Saharan dust days we found statistically significant (p b 0.05) effects of PM 10-2.5 for cardiovascular (odds ratio for increase of an interquartile range, OR = 1.033, 95% confidence interval: 1.006-1.060) and respiratory mortality (OR = 1.044, 95% CI: 1.001-1.089). During Saharan dust days strongest cardiovascular effects were found for the same fraction (OR = 1.085, 95% CI: 1.017-1.158) with an indication of effect modification (p = 0.111). Effects of PM 2.5-1 during Saharan dust days were about the double than in non-dust days for cardiovascular and respiratory mortality, but these differences were not statistically significant. Conclusion: Our results using independent fractions of PMs provide further evidence that the effects of shortterm exposure to PM during Saharan dust days are associated with both cardiovascular and respiratory mortality. A better understanding of which of the different PM size fractions brought by Saharan dust is more likely to accelerate adverse effects may help better understand mechanisms of toxicity.

This work provides the first continuous measurements of carbonaceous aerosol at the Global Atmosphere Watch (GAW) Monte Curcio regional station, within the southern Mediterranean basin. We specifically analyzed elemental carbon (EC) and organic carbon (OC) concentrations in particulate matter (PM) samples, collected from April to December during the two years of 2016 and 2017. The purpose of the study is to understand the behavior of both PM and carbonaceous species, in their fine and coarse size fraction, along with their seasonal variability. Based on 18 months of observations, we obtained a dataset that resulted in a vast range of variability. We found the maximum values in summer, mainly related to the enhanced formation of secondary pollutants owing to intense solar radiation, also due to the high frequency of wildfires in the surrounding areas, as well as to the reduced precipitation and aerosol-wet removal. We otherwise observed the lowest levels during fall, coinciding with ...

An outstanding Saharan dust event affected the Iberian Peninsula during winter 2016 (20 to 25 February). The impact of this event on ambient PM10 surface levels and its spatial and temporal evolution was investigated by means of data from 250 air quality stations across mainland Spain and the Balearic Islands. The event had a significant impact on surface PM10 levels, and on 22 February, 90% of the air quality monitoring sites registered PM10 concentrations above the EU daily limit value of 50 μg/m3. The study of the attenuated backscattering vertical profiles associated with African dust evidenced a complex structure, with a thick aerosol layer that was at higher altitudes over the pre‐Pyrenees compared to the coastal area of Barcelona but closer to the surface than typically observed at both sites. Optical and physical properties of dust particles were investigated at the continental background Global Atmosphere Watch mountain observatory of Montsec (MSA) in the pre‐Pyrenees. Good...

Se describe la composición mineralógica y elemental del contenido particulado de las lluvias de barro recogidas en el Montseny (nordeste península Ibérica) desde 1983 a 1998. Se han identificado 3 áreas-fuente en el norte de África: el Sahara occidental, el Atlas marroquí y el Sahara central. Entre zonas, se han hallado diferencias significativas en la mineralogía y contenido elemental del material particulado. Se ha analizado la frecuencia de las lluvias de barro, que presentan alta variabilidad interanual. De hecho, dos episodios aportaron el 60% del total depositado en 15 años. Estacionalmente, las lluvias de barro predominaron en primavera y otoño. Las aportaciones de cationes básicos y P de las lluvias de barro constituyen porcentajes de entre 60-100% en las entradas totales atmosféricas. Referido a la circulación de nutrientes en el ecosistema forestal, la deposición de K + , Ca +2 y Mg +2 por las lluvias de barro aporta el 27%, 45% y 84% respectivamente de las necesidades nutritivas de este encinar. Palabras clave: polvo sahariano, composición del aire, aportación de nutrientes, situaciones meteorológicas sinópticas, nordeste español, bioquímica del bosque. Summary. Red rains and the transport and deposition of saharan dust over the northeastern Iberian peninsula The African dust frequency, dust content, dust mineralogy and elemental composition have been analyzed for a site in the Montseny mountains (northeastern Spain) for the period 1983-1998. Three source regions in North Africa have been identified for the dust loaded red rains: Western Sahara, Moroccan Atlas and central Sahara. Significant differences in mineralogy have been found between source areas. The ocurrence of red rains is highly variable: two events accounted for 60% of total deposition in 15 years. Spring and autumn presented maximum number of red rain events and maximum dust deposition compared to other seasons. Element inputs in red rains accounted for 60-100% of total atmospheric inputs. These african inputs were important contributors to the holm oak forest needs at Montseny, by providing 27%, 45% and 84% respectively for K + , Ca +2 and Mg +2 fluxes needed for the annual increment of the aboveground biomass.

Concentrations of elmnents and ions were measured in aerosol samples collected between March 1992 and December 1993 at a rural station on the Mediterranean coast of Turkey. Concentrations of pollution-derived elements are lower fluan corresponding concentrations reported for the western Mediterranean region, due to the longer distances traveled by the particles to reach the eastern Mediterranean region. Concentrations of elements vary on timescales ranging frmn days to seasons. Short-term variations in the concentrations of pollution-derived elements are explained by transport from source regions. Short-term variations in the concentrations of seasalt and crustal elements, on the other hand, are due to the episodic nature of wind-induced particle generation mechanis•ns. Transport failed to explain long-term variations due to lack of seasonal changes in ,air mass transport patterns. The seasonal variations in the concentrations of anthropogenic elements are detennined by the wet deposition of particles, which is more extensive in the wet season, and distances between source regions and the sampling site. The long-term variations in the concentrations of crustal and sea-salt elements are explained by seasonal changes in their source strengths. Distant rains on the path of the air masses which transport anthropogenic particles to the eastern Mediterranean are more i•ffluential on the observed seasonal behavior of pollution-derived elmnents than local rain events.

Effects of atmospheric deposition and other environmental factors on phytoplankton dynamics were evaluated from an open (having offshore characteristics) and a coastal station in the northeastern Mediterranean between December 2000 and December 2001. Data on phytoplankton, chlorophyll a, nutrients, temperature and salinity were obtained at biweekly or more intense intervals during 1 yr, whilst transport of Saharan dust towards the sampling region was monitored daily by SeaWiFS (sea-viewing wide field-of-view sensor) images. Diatoms were the group of highest average biomass during the entire investigation period. Although coccolithophores (mainly Emiliania huxleyi) numerically dominated at the open station during the study period, their maximum abundance was as low as 50 × 10 3 cells l-1. The intensity of dust transport was observed to be highest in spring. Less intense transports were observed in summer and autumn. Several intense episodic dry and wet dust deposition events during the spring season observed by SeaWiFS images caused little or no increase in phytoplankton abundance and biomass in the following days and weeks. Nevertheless, it appears that less intense dust transport events increased phytoplankton abundance and biomass in August, September and October 2001, when water column stratification was at its peak. However, these increases were much weaker than the major winter-early spring bloom (in February and March), which was caused by upwelling, mixing the water column. We suggest that the impact of atmospheric nutrient input on phytoplankton in the Mediterranean is rather low on a yearly basis.

The Basic Environmental Observatory (BEO) at Moussala peak is the main site for permanent uninterrupted in-situ observations of atmospheric aerosol properties in southeastern Europe. It is a region, which suffers a very severe impact of Sahara dust storms due to a long-range air mass transport. Despite the large distance away from the southernmost part of the region, direct Sahara dust events (SDEs) are common for the BEO site, mainly during late winter and spring. Moreover, in many cases particles of Saharan origin have been detected over Moussala, mainly after a SDE occurring over central and southeastern Europe. This paper reports seven events registered at Moussala BEO by a 3563 TSI Nephelometer during the period between April 1 and June 30, 2013. The impact is also estimated quantitatively of the mineral dust particles on the overall optical depth for the period reported.

From 20 until 23 March 1990 an outstanding Saharan dust episode was observed at the high-alpine site Jungfraujoch (3450 m a.s.1.), Switzerland. Detailed meteorological analyses including back trajectories showed a transport of the dust-loaded airmass from the Sahara desert over the Eastern Atlantic to Central Europe. During this episode, in situ studies of the aerosol revealed significantly different properties from the background conditions usually observed at the remote site Jungfraujoch. An increase in the coarse particle number concentration was accompanied by a depletion in the ultrafine particle concentration. This unusual absence of ultrafine particles during the first 1.5 days of the episode could be explained by coagulation processes in the Saharan air mass. The distinct coarse particle mode was reflected in the total mass concentration which was higher by a factor of 30 than the annual average at Jungfraujoch. The mineralogical and elemental composition of the dust point to a source region in North and West Africa which was corroborated by the trajectory calculations. The chemical composition of aerosol particles was characterized by high concentrations of soil and sea spray tracers. A snowfall event on 20 March showed "Saharan dust characteristics" and offered the unique possibility to study in situ the scavenging phenomena. Scavenging ratios were enhanced for most components-particularly for NH2 and SO~-during this event compared to typical values found for snowfall events without Saharan dust. This was most probably due to heavy riming. This single event contributed substantially to the annual Ca 2+ and carbonate deposition at this site and could neutralize 50% of the 1991/1992 winter and spring deposition of NO~-and so,~- .

Se describe la composición mineralógica y elemental del contenido particulado de las lluvias de barro recogidas en el Montseny (nordeste península Ibérica) desde 1983 a 1998. Se han identificado 3 áreas-fuente en el norte de África: el Sahara occidental, el Atlas marroquí y el Sahara central. Entre zonas, se han hallado diferencias significativas en la mineralogía y contenido elemental del material particulado. Se ha analizado la frecuencia de las lluvias de barro, que presentan alta variabilidad interanual. De hecho, dos episodios aportaron el 60% del total depositado en 15 años. Estacionalmente, las lluvias de barro predominaron en primavera y otoño. Las aportaciones de cationes básicos y P de las lluvias de barro constituyen porcentajes de entre 60-100% en las entradas totales atmosféricas. Referido a la circulación de nutrientes en el ecosistema forestal, la deposición de K + , Ca +2 y Mg +2 por las lluvias de barro aporta el 27%, 45% y 84% respectivamente de las necesidades nutritivas de este encinar. Palabras clave: polvo sahariano, composición del aire, aportación de nutrientes, situaciones meteorológicas sinópticas, nordeste español, bioquímica del bosque. Summary. Red rains and the transport and deposition of saharan dust over the northeastern Iberian peninsula The African dust frequency, dust content, dust mineralogy and elemental composition have been analyzed for a site in the Montseny mountains (northeastern Spain) for the period 1983-1998. Three source regions in North Africa have been identified for the dust loaded red rains: Western Sahara, Moroccan Atlas and central Sahara. Significant differences in mineralogy have been found between source areas. The ocurrence of red rains is highly variable: two events accounted for 60% of total deposition in 15 years. Spring and autumn presented maximum number of red rain events and maximum dust deposition compared to other seasons. Element inputs in red rains accounted for 60-100% of total atmospheric inputs. These african inputs were important contributors to the holm oak forest needs at Montseny, by providing 27%, 45% and 84% respectively for K + , Ca +2 and Mg +2 fluxes needed for the annual increment of the aboveground biomass.

Annual volume-weighted mean (VWM) concentrations in rainwater collected at La Castanya (LC, Montseny Mountains, NE Spain) were analysed from 1983 to 2000 to study the temporal trends in precipitation chemistry, and the causes behind the changes. A significant positive correlation was found between annual rainwater SO 4 2À concentrations at LC and Spanish SO 2 emissions (r ¼ 0:73; P ¼ 0:0008) both decreasing remarkably during this period. Rainwater alkalinity increased during the period, shifting from negative values at the beginning (VWM in the 5 initial years=À2.7 meq l À1) to alkaline values in recent years (VWM in the 5 final years=18.0 meq l À1). Stepwise regression analysis indicated that 88% of the variation of alkalinity could be accounted for by the variability of non-marine Ca 2+ and non-marine SO 4 2À , with a more prominent dependence on Ca 2+. Rains of African provenance were highly enriched in alkalinity and Ca 2+ , but no significant increases in their occurrence were found for the study period. Because of the reported higher dust updraft in northern Africa during years of high North Atlantic Oscillation (NAO) index, we also explored the relationship between rainwater variables associated with an African provenance and NAO. Annual precipitation was inversely related to NAO (r ¼ À0:61; P ¼ 0:007). The annual wet deposition of African dust-related elements showed no correlation with NAO, probably because wet deposition of these elements depends on two factors (precipitation and dust updraft) which have opposite behaviour with respect to NAO. We hypothesise that dry deposition of African dust during dry spells (not sampled in this study) might be higher during high NAO-index years.

Dust events originating from the Saharan desert have far-reaching environmental impacts, but the causal mechanism of magnitude and occurrence of Saharan dust events (SDEs) during the preinstrumental era requires further research, particularly as a potential analog for future climate. Using an ultrahigh resolution glacio-chemical record from the 2013 Colle Gnifetti ice core drilled in the Swiss-Italian Alps, we reconstructed a 2000-year-long summer Saharan dust record. We analyzed both modern (1780-2006) and premodern Common Era (CE) major and trace element records to determine air mass source regions to the Colle Gnifetti glacier and assess similarities to modern and reconstructed climate trends in the Northern Hemisphere. This new proxy SDE reconstruction, produced using measurements from a novel, continuous ultrahigh-resolution (120-μm) ice core analysis method (laser ablation-inductively coupled plasma-mass spectrometer) is comprised of 316,000 data points per element covering the period 1-1820 CE. We found that the Colle Gnifetti ice core captures an anomalous increase in Saharan dust transport during the onset of the Medieval Climate Anomaly (870-1000 CE) and records other prominent shorter events (CE, 140-170, 370-450, 1320-1370, and 1910-2000), offering a framework for new insights into the implications of Saharan dust variability. Plain Language Summary Plumes of dust from the Saharan desert transported across the Atlantic Ocean and Mediterranean Sea, influence land, ocean, and atmospheric systems, yet we know relatively little about how these events varied before the instrumental record. Saharan dust transport can result in flourishing ecosystems, poor air quality, and even changes in the frequency of North Atlantic hurricanes. In our study, we develop a summer Saharan dust event record with subannual resolution from an ice core drilled in the European Alps, dating back 2000 years. The Saharan dust record shows increased dust transport is caused by a combination of enhanced high-pressure systems over the Mediterranean and drier conditions in Northern Africa, along with other atmospheric influences. Our record indicates the past century has seen an increased amount of Saharan dust transport, comparable to large occurrences over the past 2000 years. Additionally, we discuss implications for using our subannually resolved Saharan dust record in concert with historical records to improve interpretations of human-climate interactions.

Desert areas in North Africa are important sources of mineral dust to the atmosphere, which upon deposition can influence oceanic and terrestrial biogeochemical cycles and affect forest productivity. Here, an increase of the Ž. frequency of rainfall loaded with such dust red rain in the last decades is documented for a site in northeastern Spain. The relevance of such a trend for the neutralization of acid rain and the delivery of nutrients in significant amounts to Mediterranean ecosystems is described.

Annual volume-weighted mean (VWM) concentrations in rainwater collected at La Castanya (LC, Montseny Mountains, NE Spain) were analysed from 1983 to 2000 to study the temporal trends in precipitation chemistry, and the causes behind the changes. A significant positive correlation was found between annual rainwater SO 4 2À concentrations at LC and Spanish SO 2 emissions (r ¼ 0:73; P ¼ 0:0008) both decreasing remarkably during this period. Rainwater alkalinity increased during the period, shifting from negative values at the beginning (VWM in the 5 initial years=À2.7 meq l À1) to alkaline values in recent years (VWM in the 5 final years=18.0 meq l À1). Stepwise regression analysis indicated that 88% of the variation of alkalinity could be accounted for by the variability of non-marine Ca 2+ and non-marine SO 4 2À , with a more prominent dependence on Ca 2+. Rains of African provenance were highly enriched in alkalinity and Ca 2+ , but no significant increases in their occurrence were found for the study period. Because of the reported higher dust updraft in northern Africa during years of high North Atlantic Oscillation (NAO) index, we also explored the relationship between rainwater variables associated with an African provenance and NAO. Annual precipitation was inversely related to NAO (r ¼ À0:61; P ¼ 0:007). The annual wet deposition of African dust-related elements showed no correlation with NAO, probably because wet deposition of these elements depends on two factors (precipitation and dust updraft) which have opposite behaviour with respect to NAO. We hypothesise that dry deposition of African dust during dry spells (not sampled in this study) might be higher during high NAO-index years.

The intercontinental transportation of mineral material from Africa to the Caribbean, North America and South America is an international phenomenon of research interest. Several studies have drawn attention of meteorological effects and climatic implications resulting from the presence of this aerosol in the atmosphere, as well as its potential adverse effects on human health.The Colombian Caribbean region is not immune to this problem, although there are few studies about it. Therefore, the aim of this paper is to identify events of intrusion of African dust over the Caribbean region of Colombia. The procedure followed in this investigation was the analysis of dust concentration maps generated by the GEOS-5, SKIRON, NAAPS and CALIPSO models between 01 January and 31 December 2012. Images generated by the MODIS satellite sensor and data from regional air quality monitoring network were also used. According to the results obtained, there are evidences that confirm that in the north ...

This paper presents a new empirical equation relating horizontal visibility and PM 10 dust concentrations. The new empirical equation (IZO-Eq) is derived from observations performed at the Izaña Atmospheric Observatory (IZO, 28.30ºN, 16.49ºW, 2367 m a.s.l., Tenerife, Spain), recorded during Saharan dust outbreaks from 2003 to 2010. A filter based on relative humidity, present-weather and aerosol optical properties is applied to identify dust events. IZO-Eq is validated in the Sahel region during the dry and wet seasons (2006-2008) using data from two PM 10 monitoring stations from the African Monsoon Multidisciplinary Analysis (AMMA) International project, and data from the nearest meteorological synoptic stations. The estimated PM 10 derived from IZO-Eq is compared against that those obtained by other empirical equations and dust surface concentrations from NMMB/BSC-Dust model. IZO-Eq presents better performance than the other equations in both dry and wet seasons when compared with observed PM 10 at two Sahelian sites. IZO-Eq is also able to reproduce the surface concentration variability simulated by NMMB/BSC-Dust. Above 10 km of horizontal visibility, empirical equations cannot be used to estimate PM 10 , since above this threshold equations estimate a nearly constant PM 10 value, regardless of the visibility range. A comparison between the PM 10 spatial distributions derived from visibility SYNOP observations through IZO-Eq, the modelled values from the NMMB/BSC-Dust model and aerosol optical depth (AOD) retrieved from MODIS is performed for the 2006-2008 period. The different spatial distributions present a rather good agreement among them as well as to reproduce the characteristic seasonal dust features over North Africa.

Events of very high concentrations of 7 Be cosmogenic radionuclide have been recorded in the subpolar regions of Europe during the cold season. With an aim to investigate the mechanisms responsible for those peak 7 Be events, and in particular to verify if they are associated with the fast descent of stratospheric air masses occurring during sudden stratospheric warming (SSWs), we analyse 7 Be observations at six sampling sites in Scandinavia during January-March 2003 when very high 7 Be concentrations were observed and the Arctic vortex was relatively unstable as a consequence of several SSWs. We use the GEOS-Chem chemistry and transport model driven by the MERRA-2 meteorological reanalysis to simulate tropospheric 7 Be over Northern Europe. We show that the model reasonably reproduces the temporal evolution of surface 7 Be concentrations observed at the six sampling sites. Our analysis of model simulations, surface 7 Be observations, as well as atmospheric soundings of ozone and temperature indicates that the 7 Be peak observed in late February 2003 (between 20 and 28 February 2003) at the six sampling sites in Scandinavia was associated with downward transport of stratospheric vortex air originated during SSW that occurred a few days before the peak (18-21 February 2003).

During the last 7-year period (2000-2006) atmosphere circulation changes show strong influences on the dust storm deposition dynamics and, as a result, on the primary production dynamics of the northwest African Upwelling System. From 2000 to 2006, the annual mean sea level pressure became higher ranging from 1014 to 1015 mb. Mean annual zonal wind intensity became higher (from 1.1 to 1.8 m s-1), while the mean annual meridional was reduced from 6.2 to 5.3 m s-1 at the north of the Canary Islands. Mean annual satellitederived AVHRR/NOAA SST recorded in the northwest African Upwelling became warmer in both locations, from 18.3ºC to 18.8ºC in Cape Ghir and from 19.5ºC to 20.3ºC north Canary Islands waters. CHL records from the SeaWiFS/OV-2 showed a different pattern trend. Mean annual CHL levels increased at Cape Ghir from 0.65 mg m-3 to 0.9 mg m-3 and significantly reduced from 0.59 mg m-3 to 0.31 mg m-3 at the north of the Canary Islands. Changes observed in the role of CHL during the last 7-years period could be associated to intensive dust deposition and exceptional weather warming observed in this area since 2000. However, this study focused on a 7-year period and conclusions on possible links between dust deposition and marine biochemistry activity cannot be generalized.

The aim of this study was to determine the effect of meteorological factors on the concentration of beryllium 7Be and lead 210Pb in the surface layer air on background their variability due to environmental conditions. Data analysis was carried out for 13 Polish stations for the period 2005-2009. The measurement cosmogenic and terrestrial radioactivity were collected on network station type ASS-500. The analysis includes the following meteorological elements from NWS stations: temperature, precipitation, atmospheric pressure, wind speed, humidity, solar radiation and in addition number of sunspots (SSN). It was considered that these meteorological elements mainly responsible for the transport and removal processes of 7Be and 210Pb from the atmosphere. The study method was used correlation analysis. Because of the relatively small area of Poland, it is hard to prove the dependence of 7Be activity concentration variability on the influence of such factors as geographical location or S...

A field campaign was performed simultaneously at five measurement sites, having different characteristics, to characterize the spatial distribution of the carbonaceous content in atmospheric aerosol in Southern Italy during the winter season. Organic carbon (OC) and elemental carbon (EC) were measured at urban (Naples), suburban (Lecce), coastal/marine (Lamezia Terme and Capo Granitola), and remote (Monte Curcio) locations. OC and EC mass concentrations were quantified by the thermal-optical transmission (TOT) method, in 24-h PM 10 and PM 2.5 samples collected on quartz fiber filters, from 25 November 2015 to 1 January 2016. The different sites showed marked differences in the average concentrations of both carbonaceous species. Typically, OC average levels (±standard deviation) were higher at the sites of Naples (12.8 ± 5.1 and 11.8 ± 4.6 µg/m 3) and Lecce (10.7 ± 5.8 and 9.0 ± 4.7 µg/m 3), followed by Lamezia Terme (4.3 ± 2.0 and 4.0 ± 1.9 µg/m 3), Capo Granitola (2.3 ± 1.2 and 1.7 ± 1.1 µg/m 3), and Monte Curcio (0.9 ± 0.3 and 0.9 ± 0.3 µg/m 3) in PM 10 and PM 2.5 , respectively. Similarly, EC average levels (±standard deviation) were higher at the urban sites of Naples (2.3 ± 1.1 and 1.8 ± 0.5 µg/m 3) and Lecce (1.5 ± 0.8 and 1.4 ± 0.7 µg/m 3), followed by Lamezia Terme (0.6 ± 0.3 and 0.6 ± 0.3 µg/m 3), Capo Granitola (0.3 ± 0.3 and 0.3 ± 0.2 µg/m 3), and Monte Curcio (0.06 ± 0.04 and 0.05 ± 0.03 µg/m 3) in PM 10 and PM 2.5 , respectively. An opposite trend was observed for the OC/EC ratios ranging from 6.4 to 15.9 in PM 10 and from 6.4 to 15.5 in PM 2.5 with lower values in urban sites compared to remote sites. Different OC-EC correlations, 0.36 < R 2 < 0.90, were found in four observation sites. This behavior suggests the contributions of similar sources and common atmospheric processes in both fractions. No correlations were observed between OC and EC at the site of Naples. The average secondary organic carbon (SOC) concentrations, quantified using the minimum OC/EC ratio method, ranged from 0.4 to 7.6 µg/m 3 in PM 10 and from 0.4 to 7.2 µg/m 3 in PM 2.5 , accounting from 37 to 59% of total OC in PM 10 and from 40 to 57% in PM 2.5 with higher percentages in the urban and suburban sites of Naples and Lecce.

In total 562 daily PM 10 and PM 2:5 samples were collected from April 2001 to April 2002 at a rural site (Erdemli) located on the coast of the Eastern Mediterranean. The annual mean PM 10 and PM 2:5 levels were 36:4 AE 27:8 and 9:7 AE 5:9 mg m À3 , respectively. PM 10 and PM 2:5 concentrations indicated orders of magnitude change from day to day (PM 10 ¼ 22326 mg m À3 ; PM 2:5 ¼ 0:5228 mg m À3). The highest levels of PM 10 were observed during the transition period (March, April and May) due to mineral dust transported from North Africa and during winter due to sea spray generation. However, PM 2:5 levels exhibited higher concentrations during summer resulting from an enhanced production of secondary aerosols. The PM 2:5 =PM 10 ratio (0.25) and categorization of air mass back trajectories indicated that PM 10 at the study area is dominated by primary aerosol emissions (mineral dust particles from the Saharan Desert and sea salt particles from the Mediterranean Sea itself). During the whole sampling period 28 and 51 events exceeded the recommended maximum values of 50 and 15 mg m À3 for PM 10 and PM 2:5 , respectively. Source apportionment analysis indicated that PM 10 exceedances originated as a consequence of natural events (mineral dust $40%; sea salt $50%) whereas PM 2:5 exceedances were accounted primarily by pollution events (in 90% of the cases).

El texto es un proyecto de estudio del curso 2.º de Bachillerato de Investigación Excelencia del IES Andrés Laguna, centrado en las alteraciones atmosféricas en el Círculo Polar Ártico. Está escrito por Arturo Francisco Barbero e incluye una serie de secciones que abarcan desde generalidades hasta conclusiones y bibliografía. Las secciones principales incluyen introducción, instrumentación, finalidad, metodología, análisis e interpretación de datos, y conclusiones. Se utilizan herramientas como AERONET, CALIPSO y HYSPLIT para recopilar y analizar datos sobre aerosoles atmosféricos, espesor óptico de aerosoles y otros parámetros relacionados con la atmósfera en el Círculo Polar Ártico.

Atmospheric analysis data from the European Center for Medium-Range Weather Forecasts (ECMWF) have been acquired and are used to characterize the meteorological situation in Maroua, Cameroon (10.614 • N, 14.361 • E) at 12:00 UTC. These are then used to simulate downward global solar radiation (DGSR) with the moderate-resolution transmittance (MODTRAN) radiative transfer code (RTC). In comparison with meteorological data measured during the year 2014 in Maroua, ECMWF atmospheric quantities at ground level, in general, showed good correlation coefficients and slight differences. It is shown that ECMWF atmospheric profiles can thus be used to complete the scarce atmospheric data and to study the atmosphere state and dynamics, such as the African monsoon phenomenon detected in this region, which regulates the rainy season. In addition, they are more suitable to simulate clear-sky DGSR compared to MODTRAN standard atmospheric profiles. The causes and effects of the substantial bias and weak correlation coefficient observed with ECMWF wind data and the constant underestimation of simulated DGSR in comparison with ground-based measurements are investigated. The paper emphasizes the need for a better characterization of the Maroua atmosphere state and dynamics as well as the simulation of more accurate and reliable DGSR under any atmospheric conditions.

In this study, the aim was to model the toxic effect of copper (Cu) and analyse the removal of Cu in aqueous Saharan and non-Saharan mediums by Lemna minor. Two separate test groups were formed: with Saharan dust (S) and without Saharan dust (WS). These test groups were exposed to 3 different Cu concentrations (0.05, 0.50 and 5.00 ppm). Time, concentration, and group-dependent removal effi ciencies were compared using the non-parametric Mann-Whitney U test and statistically signifi cant differences were found. The optimum removal values were tested at the highest concentration 79.6% in the S medium and observed on the 4th day for all test groups. The lowest removal value (16%) was observed at 0.50 ppm on the 1st day in the WS medium. When the S medium and WS medium were compared, in all test groups Cu was removed more successfully in the S medium than the WS medium contaminated by Cu in 3 different concentrations of (0.05 ppm, 0.50 ppm, 5.00 ppm). The regression analysis was also tested for all prediction models. Different models were performed and it was found that cubic models show the highest predicted values (R 2). The R 2 values of the estimation models were found to be at the interval of 0.939-0.991 in the WS medium and 0.995-1.000 in the S medium.

The Puerto Rico Dust Experiment (PRIDE) took place in Roosevelt Roads, Puerto Rico from 26 June to 24 July 2000 to study the radiative and physical properties of African dust aerosol transported into the region. PRIDE had the unique distinction of being the first major field experiment to allow direct comparison of aerosol retrievals from the Moderate Imaging Spectroradiometer (MODIS) with Sun photometer and in situ aerosol measurements. Over the ocean the MODIS algorithm retrieves aerosol optical depth (AOD) as well as information about the aerosols&#39; size distribution. During PRIDE, AODs derived by MODIS in the red wavelengths (0.66 μm) compare closely with Sun photometers. However, MODIS‐derived AODs are too large in the blue and green wavelengths (0.47 and 0.55 μm) and too small in the near infrared (0.87 μm). This error in AOD spectral dependence results in retrieved particle size distributions that are small compared to in situ measurements and smaller still when compared t...

Plate tectonics is driven by Earth-Moon barycentre shifts in the lower mantle. The eastern Canary Islands have geographic and geological conditions derived from the movements of the Central American plates. Some features of these islands are influenced by the rotation of the Earth from west to east in the evolution of the marine currents that surround them and the opening of the North Atlantic to the North Pole with little dependence of the glacial isostatic adjustment (GIA). In addition, their position with respect to the Tropic of Cancer and the African continent affect the north-south and east-west climatic change dynamics and their tectonic stability respectively. Dated lavas contain marine and aeolian deposits and some of the Pleistocene marine deposits indicate higher sea level in cooler circumstances, which is anomalous. Relating those marine deposits produced during the warmest interglacial, the last interglacial and the Holocene with their equivalents in the Southern Hemisphere, they reflect shifts in the barycentre. Thanks to Holocene radiocarbon, topographic and day length data and alkenone temperature, we describe a mechanism by which the oscillation of the Moon's inclination (and declination) reaches extreme values (14˚ and 34˚; about 4.9˚ more than current values) approximately every 1450 years. These values occur when there is a harmonic distortion in surface areas of the Earth's crust as response associated with oscillations in the displacements of the barycentre of the Earth-Moon How to cite this paper:

The aim of this study was to determine the effect of meteorological factors on the concentration of beryllium 7Be and lead 210Pb in the surface layer air on background their variability due to environmental conditions. Data analysis was carried out for 13 Polish stations for the period 2005-2009. The measurement cosmogenic and terrestrial radioactivity were collected on network station type ASS-500. The analysis includes the following meteorological elements from NWS stations: temperature, precipitation, atmospheric pressure, wind speed, humidity, solar radiation and in addition number of sunspots (SSN). It was considered that these meteorological elements mainly responsible for the transport and removal processes of 7Be and 210Pb from the atmosphere. The study method was used correlation analysis. Because of the relatively small area of Poland, it is hard to prove the dependence of 7Be activity concentration variability on the influence of such factors as geographical location or S...

Beryllium 7 Be appears in the surface layers of the atmospheric boundary layer (ABL) as a result of stratosphere to troposphere air mass exchange (STE). Stratosphere to troposphere air mass transport (STT) can sometimes be accompanied by the origin of stratospheric ozone (O 3). The aim of this study was to attempt to answer the question as to whether 7 Be can be a good marker of stratospheric ozone origin in the concentration of ground-level ozone in the surface ABL. Eight sets of data covering the period 2002-2009 were examined: weekly concentrations of 7 Be and hourly O 3 measured in the ground level of the atmosphere. The measuring sites were at two different locations in Poland: Gdynia and Warsaw. Both locations show the maximum 7 Be concentration in spring and summer, and the minimum in late autumn and winter. In 2002-2009, the average concentration standard deviations of 7 Be were 3.336±1.312 mBq/m 3 and 2.907±0.030 mBq/m 3 , respectively, for Gdynia and Warsaw. The data obtai...

Desert areas in North Africa are important sources of mineral dust to the atmosphere, which upon deposition can influence oceanic and terrestrial biogeochemical cycles and affect forest productivity. Here, an increase of the Ž. frequency of rainfall loaded with such dust red rain in the last decades is documented for a site in northeastern Spain. The relevance of such a trend for the neutralization of acid rain and the delivery of nutrients in significant amounts to Mediterranean ecosystems is described.

A prominent Saharan Air Layer (SAL) was detected over the Northern Atlantic from the West African Coast to the Caribbean Sea in 2007. Data was collected from the Aerosols and Ocean Science Expedition (AEROSE), which encountered a major dust outflow on 13 and 14 May 2007. These observational measurements came from onboard instrumentation and radiosondes that captured the dust-front event from 13 to 14 May 2007. Aerosol backscatter was confined within the Marine Boundary Layer (MBL), with layers detected up to 3 km. Aerosol Optical Depth (AOD) increased by one order of magnitude during the dust front, from 0.1 to 1. Downward solar radiation was also attenuated by 200 W/m2 and 100 W/m2 on the first and second days, respectively. A weaker gradient at and above 500 m from potential temperature profiles indicates a less-defined MBL, and an ambient air temperature of 26 °C on 14 May and 28 °C on 15 May were observed above 500 m, reinforcing the temperature inversion and static stability of...

Surface concentration of black carbon (BC) is a key factor for the understanding of the impact of anthropogenic pollutants on human health. The majority of Italian cities lack long-term measurements of BC concentrations since such a metric is not regulated by EU legislation. This work attempts a long-term (2001-2017) inference of equivalent black carbon (eBC) concentrations in the city of Rome (Italy) based on sun-photometry data. To this end, aerosol light absorption coefficients at the surface are inferred from the "columnar" aerosol aerosol light absorption coefficient records from the Rome Tor Vergata AERONET sun-photometer. The main focus of this work is to rescale aerosol light absorption columnar data (AERONET) to ground-level BC data. This is done by using values of mixing layer height (MLH) derived from ceilometer measurements and then by converting the absorption into eBC mass concentration through a mass-to-absorption conversion factor, the Mass Absorption Efficiency (MAE). The final aim is to obtain relevant data representative of the BC aerosol at the surface (i.e., in-situ)-so within the MLH-and then to infer a long-term record of "surface" equivalent black carbon mass concentration in Rome. To evaluate the accuracy of this procedure, we compared the AERONET-based results to in-situ measurements of aerosol light absorption coefficients (α abs) collected during some intensive field campaigns performed in Rome between 2010 and 2017. This analysis shows that different measurement methods, local emissions, and atmospheric conditions (MLH, residual layers) are some of the most important factors influencing differences between inferred and measured α abs. As a general result, "inferred" and "measured" α abs resulted to reach quite a good correlation (up to r = 0.73) after a screening procedure that excludes one of the major cause of discrepancy between AERONET inferred and in-situ measured α abs : the presence of highly absorbing aerosol layers at high altitude (e.g., dust), which frequently affects the Mediterranean site of Rome. Long-term trends of "inferred" α abs , eBC, and of the major optical variables that control aerosol's direct radiative forcing (extinction aerosol optical depth, AOD EXT , absorption aerosol optical depth, AOD ABS , and single scattering albedo, SSA) have been estimated. The Mann-Kendall statistical test associated with Sen's slope was used to test the data for long-term trends. These show a negative trend for both AOD EXT (−0.047/decade) and AOD ABS (−0.007/decade). The latter converts into a negative trend for the α abs of −5.9 Mm −1 /decade and for eBC mass concentration of −0.76 µg/m 3 /decade. A positive trend is found for SSA (+0.014/decade), indicating that contribution of absorption to extinction is decreasing faster than that of scattering. These long-term trends are consistent with those of other air pollutant concentrations (i.e., PM 2.5 and CO) in the Rome area.

During the last 7-year period (2000-2006) atmosphere circulation changes show strong influences on the dust storm deposition dynamics and, as a result, on the primary production dynamics of the northwest African Upwelling System. From 2000 to 2006, the annual mean sea level pressure became higher ranging from 1014 to 1015 mb. Mean annual zonal wind intensity became higher (from 1.1 to 1.8 m s-1), while the mean annual meridional was reduced from 6.2 to 5.3 m s-1 at the north of the Canary Islands. Mean annual satellitederived AVHRR/NOAA SST recorded in the northwest African Upwelling became warmer in both locations, from 18.3ºC to 18.8ºC in Cape Ghir and from 19.5ºC to 20.3ºC north Canary Islands waters. CHL records from the SeaWiFS/OV-2 showed a different pattern trend. Mean annual CHL levels increased at Cape Ghir from 0.65 mg m-3 to 0.9 mg m-3 and significantly reduced from 0.59 mg m-3 to 0.31 mg m-3 at the north of the Canary Islands. Changes observed in the role of CHL during the last 7-years period could be associated to intensive dust deposition and exceptional weather warming observed in this area since 2000. However, this study focused on a 7-year period and conclusions on possible links between dust deposition and marine biochemistry activity cannot be generalized.

Effects of atmospheric deposition and other environmental factors on phytoplankton dynamics were evaluated from an open (having offshore characteristics) and a coastal station in the northeastern Mediterranean between December 2000 and December 2001. Data on phytoplankton, chlorophyll a, nutrients, temperature and salinity were obtained at biweekly or more intense intervals during 1 yr, whilst transport of Saharan dust towards the sampling region was monitored daily by SeaWiFS (sea-viewing wide field-of-view sensor) images. Diatoms were the group of highest average biomass during the entire investigation period. Although coccolithophores (mainly Emiliania huxleyi) numerically dominated at the open station during the study period, their maximum abundance was as low as 50 × 10 3 cells l-1. The intensity of dust transport was observed to be highest in spring. Less intense transports were observed in summer and autumn. Several intense episodic dry and wet dust deposition events during the spring season observed by SeaWiFS images caused little or no increase in phytoplankton abundance and biomass in the following days and weeks. Nevertheless, it appears that less intense dust transport events increased phytoplankton abundance and biomass in August, September and October 2001, when water column stratification was at its peak. However, these increases were much weaker than the major winter-early spring bloom (in February and March), which was caused by upwelling, mixing the water column. We suggest that the impact of atmospheric nutrient input on phytoplankton in the Mediterranean is rather low on a yearly basis.

The Basic Environmental Observatory (BEO) at Moussala peak is the main site for permanent uninterrupted in-situ observations of atmospheric aerosol properties in southeastern Europe. It is a region, which suffers a very severe impact of Sahara dust storms due to a long-range air mass transport. Despite the large distance away from the southernmost part of the region, direct Sahara dust events (SDEs) are common for the BEO site, mainly during late winter and spring. Moreover, in many cases particles of Saharan origin have been detected over Moussala, mainly after a SDE occurring over central and southeastern Europe. This paper reports seven events registered at Moussala BEO by a 3563 TSI Nephelometer during the period between April 1 and June 30, 2013. The impact is also estimated quantitatively of the mineral dust particles on the overall optical depth for the period reported.

The Puerto Rico Dust Experiment (PRIDE) took place in Roosevelt Roads, Puerto Rico from 26 June to 24 July 2000 to study the radiative and physical properties of African dust aerosol transported into the region. PRIDE had the unique distinction of being the first major field experiment to allow direct comparison of aerosol retrievals from the Moderate Imaging Spectroradiometer (MODIS) with Sun photometer and in situ aerosol measurements. Over the ocean the MODIS algorithm retrieves aerosol optical depth (AOD) as well as information about the aerosols&#39; size distribution. During PRIDE, AODs derived by MODIS in the red wavelengths (0.66 μm) compare closely with Sun photometers. However, MODIS‐derived AODs are too large in the blue and green wavelengths (0.47 and 0.55 μm) and too small in the near infrared (0.87 μm). This error in AOD spectral dependence results in retrieved particle size distributions that are small compared to in situ measurements and smaller still when compared t...

A ten-month field study aimed to determine the contribution of natural events (i.e. sea-salt and mineral dust events) to urban PM concentration was carried out at six sampling sites in Central Italy (Lazio region). Four indicators have been used to identify natural events during the period of the study. The first one is constituted by the ratio between number of particles in the coarse to the accumulation mode. It is simple, cheap, and the information are given in quasi-real time, but the nature of the event (sea-salt or mineral dust) is not detectable. The second indicator relies on the chemical analysis of the collected PM by X-ray fluorescence (XRF) and allows a robust identification of sea-salt and crustal components. The third one is based on diagnostic ratios of elemental fractions: Mg extractable / Ti residue for sea-salt and Ti residue /Sb residue for mineral dust. It requires skilled staff but it is most accurate and sensible. The last indicator, constructed on the basis of natural radioactivity data, is not diagnostic for the nature of the event but it is able to estimate the increase in PM concentration with respect to the expected concentration in the absence of natural events. The relevance of natural events and the variations in PM concentration and composition during the study are discussed. The joined use of the four indicators allowed the identification of about 20 natural PM episodes. In general, sea-salt aerosol events did not cause exceedance of the daily EU limit value for PM 10. Saharan dust events, instead, were in most cases responsible for the exceedance of the limit value at all stations.

The intercontinental transportation of mineral material from Africa to the Caribbean, North America and South America is an international phenomenon of research interest. Several studies have drawn attention of meteorological effects and climatic implications resulting from the presence of this aerosol in the atmosphere, as well as its potential adverse effects on human health.The Colombian Caribbean region is not immune to this problem, although there are few studies about it. Therefore, the aim of this paper is to identify events of intrusion of African dust over the Caribbean region of Colombia. The procedure followed in this investigation was the analysis of dust concentration maps generated by the GEOS-5, SKIRON, NAAPS and CALIPSO models between 01 January and 31 December 2012. Images generated by the MODIS satellite sensor and data from regional air quality monitoring network were also used. According to the results obtained, there are evidences that confirm that in the north ...

This paper presents a new empirical equation relating horizontal visibility and PM 10 dust concentrations. The new empirical equation (IZO-Eq) is derived from observations performed at the Izaña Atmospheric Observatory (IZO, 28.30ºN, 16.49ºW, 2367 m a.s.l., Tenerife, Spain), recorded during Saharan dust outbreaks from 2003 to 2010. A filter based on relative humidity, present-weather and aerosol optical properties is applied to identify dust events. IZO-Eq is validated in the Sahel region during the dry and wet seasons (2006-2008) using data from two PM 10 monitoring stations from the African Monsoon Multidisciplinary Analysis (AMMA) International project, and data from the nearest meteorological synoptic stations. The estimated PM 10 derived from IZO-Eq is compared against that those obtained by other empirical equations and dust surface concentrations from NMMB/BSC-Dust model. IZO-Eq presents better performance than the other equations in both dry and wet seasons when compared with observed PM 10 at two Sahelian sites. IZO-Eq is also able to reproduce the surface concentration variability simulated by NMMB/BSC-Dust. Above 10 km of horizontal visibility, empirical equations cannot be used to estimate PM 10 , since above this threshold equations estimate a nearly constant PM 10 value, regardless of the visibility range. A comparison between the PM 10 spatial distributions derived from visibility SYNOP observations through IZO-Eq, the modelled values from the NMMB/BSC-Dust model and aerosol optical depth (AOD) retrieved from MODIS is performed for the 2006-2008 period. The different spatial distributions present a rather good agreement among them as well as to reproduce the characteristic seasonal dust features over North Africa.