scholarly journals Significant variations of trace gas composition and aerosol properties at Mt. Cimone during air mass transport from North Africa – contributions from wildfire emissions and mineral dust

2009 ◽  
Vol 9 (14) ◽  
pp. 4603-4619 ◽  
Author(s):  
P. Cristofanelli ◽  
A. Marinoni ◽  
J. Arduini ◽  
U. Bonafè ◽  
F. Calzolari ◽  
...  
Keyword(s):  
North Africa ◽  
Fine Particles ◽  
Mineral Dust ◽  
Chemical Characterization ◽  
Anthropogenic Pollution ◽  
Trace Gas ◽  
Particle Volume ◽  
Air Mass ◽  
Air Masses ◽  
Mass Circulation

Abstract. High levels of trace gas (O3 and CO) and aerosol (BC, fine and coarse particle volumes), as well as high scattering coefficient (σp) values, were recorded at the regional GAW-WMO station of Mt. Cimone (CMN, 2165 m a.s.l., Italy) during the period 26–30 August 2007. Analysis of air-mass circulation, aerosol chemical characterization and trace gas and aerosol enhancement ratios (ERs), showed that high O3 and aerosol levels were likely linked to (i) the transport of anthropogenic pollution from northern Italy, and (ii) the advection of air masses rich in mineral dust and biomass burning (BB) products from North Africa. In particular, during the advection of air masses from North Africa, the CO and aerosol levels (CO: 175 ppbv, BC: 1015 ng/m3, fine particle volume: 3.00 μm3 cm−3, σp: 84.5 Mm−1) were even higher than during the pollution event (CO: 138 ppbv, BC: 733 ng/m3, fine particles volume: 1.58 μm3 cm−3, σp: 44.9 Mm

scholarly journals Significant variations of trace gas composition and aerosol properties at Mt. Cimone during air mass transport from North Africa – contributions from wildfire emissions and mineral dust

2009 ◽  
Vol 9 (2) ◽  
pp. 7825-7872 ◽  
Author(s):  
P. Cristofanelli ◽  
A. Marinoni ◽  
J. Arduini ◽  
U. Bonafè ◽  
F. Calzolari ◽  
...  
Keyword(s):  
North Africa ◽  
Mediterranean Basin ◽  
Mineral Dust ◽  
Northern Italy ◽  
Radiative Properties ◽  
Trace Gas ◽  
Air Mass ◽  
Air Masses ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. High levels of trace gas (O3 and CO) and aerosol (BC, fine and coarse particles) concentrations, as well as high scattering coefficient (σs) values, were recorded at the regional GAW-WMO station of Mt. Cimone (MTC, 2165 m a.s.l., Italy) during the period 26–30 August 2007. Analysis of air-mass circulation, aerosol chemical characterization and trace gas and aerosol emission ratios (ERs), showed that high O3 and aerosol levels were likely linked to (i) the transport of anthropogenic pollution from Northern Italy, and (ii) the advection of air masses rich in mineral dust and biomass burning (BB) products from North Africa. In particular, during the advection of air masses from North Africa, the CO and aerosol levels (CO: 175 ppbv, BC: 1015 ng/m3, fine particle: 83.8 cm−3, σs: 84.5 Mm−1) were even higher than during the pollution event (CO: 138 ppbv, BC: 733 ng/m3, fine particles: 41.5 cm−3, σs: 44.9 Mm−1). Moreover, despite the presence of mineral dust able to significantly affect the O3 concentration, the analysis of ERs showed that the BB event represented an efficient source of fine aerosol particles (e.g. BC), but also of the O3 recorded at MTC. The results suggest that events of mineral dust mobilization and wildfire emissions over North Africa could significantly influence radiative properties (as deduced from σs observations at MTC) and air quality over the Mediterranean basin and Northern Italy. Since in the future it is expected that wildfire and Saharan dust transport frequency could increase in the Mediterranean basin due to more frequent and severe droughts, similar events will possibly play an important role in influencing the climate and the tropospheric composition over South Europe.

scholarly journals Particle characterization at the Cape Verde atmospheric observatory during the 2007 RHaMBLe intensive

2009 ◽  
Vol 9 (5) ◽  
pp. 22739-22771 ◽  
Author(s):  
K. Müller ◽  
S. Lehmann ◽  
D. van Pinxteren ◽  
T. Gnauk ◽  
N. Niedermeier ◽  
...  
Keyword(s):  
Fine Particles ◽  
Mineral Dust ◽  
Sampling Site ◽  
Methanesulfonic Acid ◽  
Chemical Characterization ◽  
Carbonaceous Material ◽  
Cape Verde ◽  
Sea Salt ◽  
Air Masses ◽  
Coarse Mode

Abstract. The chemical characterization of filter high volume (HV) and Berner impactor (BI) samples PM during RHaMBLe 2007 shows that the Cape Verde aerosol particles are mainly composed of sea salt, mineral dust and associated water. The influence from the African continent on the aerosol constitution was generally small but air masses which came from south-western Europe crossing the Canary Islands transported dust to the sampling site together with other loadings. The mean mass concentration was determined for PM10 as 17 μg/m3 from the impactor samples and as 24.2 μg/m3 from HV filter samples. Non sea salt (nss) components of PM were found in the submicron fractions including nitrate in the coarse mode fraction. Bromide was found in all samples with much depleted concentrations in the range 1–8 ng/m3 compared to fresh sea salt aerosol indicating intense atmospheric halogen chemistry. A chloride deficit of 31% and 38% for the coarse mode particles (3.5–10 μm; 1.2–3.5 μm), of 67% (0.42–1.2 μm) and 83% (0.14–0.42 μm) for the submicron fractions was determined. During 14 May with high mineral dust loads also the maximum of OC (1.71 μg/m3) and EC (1.25 μg/m3) was measured. The minimum of TC (0.25 μg/m3) was detected during the period 25 to 27 May when pure marine air masses arrived. The concentrations of carbonaceous material decrease with increasing particles size from 60% for the ultra fine particles to 2.5% in coarse mode PM. Total iron (dust vs. non-dust: 0.53 vs. 0.06 μg m−3), calcium (0.22 vs. 0.03 μg m−3) and potassium (0.33 vs. 0.02 μg m−3) were found as good indicators for dust periods because of their heavily increased concentration in the 1.2 to 3.5 μm fraction as compared to their concentration during the non-dust periods. For the organic constituents, oxalate (78–151 ng/m3) and methanesulfonic acid (MSA, 25–100 ng/m3) are the major compounds identified. A good correlation between nss-sulphate and MSA was found for the majority of days indicating active DMS chemistry and low anthropogenic influences.

scholarly journals Long-term real-time chemical characterization of submicron aerosols at Montsec (southern Pyrenees, 1570 m a.s.l.)

2015 ◽  
Vol 15 (6) ◽  
pp. 2935-2951 ◽  
Author(s):  
A. Ripoll ◽  
M. C. Minguillón ◽  
J. Pey ◽  
J. L. Jimenez ◽  
D. A. Day ◽  
...  
Keyword(s):  
Real Time ◽  
Long Range ◽  
Chemical Characterization ◽  
Western Mediterranean ◽  
Continuous Increase ◽  
Air Mass ◽  
Air Masses ◽  
Diurnal Cycles ◽  
Western Mediterranean Basin ◽  
Air Mass Origin

Abstract. Real-time measurements of inorganic (sulfate, nitrate, ammonium, chloride and black carbon (BC)) and organic submicron aerosols (particles with an aerodynamic diameter of less than 1 μm) from a continental background site (Montsec, MSC, 1570 m a.s.l.) in the western Mediterranean Basin (WMB) were conducted for 10 months (July 2011–April 2012). An aerosol chemical speciation monitor (ACSM) was co-located with other online and offline PM1 measurements. Analyses of the hourly, diurnal, and seasonal variations are presented here, for the first time, for this region. Seasonal trends in PM1 components are attributed to variations in evolution of the planetary boundary layer (PBL) height, air mass origin, and meteorological conditions. In summer, the higher temperature and solar radiation increases convection, enhancing the growth of the PBL and the transport of anthropogenic pollutants towards high altitude sites. Furthermore, the regional recirculation of air masses over the WMB creates a continuous increase in the background concentrations of PM1 components and causes the formation of reservoir layers at relatively high altitudes. The combination of all these atmospheric processes results in a high variability of PM1 components, with poorly defined daily patterns, except for the organic aerosols (OA). OA was mostly composed (up to 90%) of oxygenated organic aerosol (OOA), split in two types: semivolatile (SV-OOA) and low-volatility (LV-OOA), the rest being hydrocarbon-like OA (HOA). The marked diurnal cycles of OA components regardless of the air mass origin indicates that they are not only associated with anthropogenic and long-range-transported secondary OA (SOA) but also with recently produced biogenic SOA. Very different conditions drive the aerosol phenomenology in winter at MSC. The thermal inversions and the lower vertical development of the PBL leave MSC in the free troposphere most of the day, being affected by PBL air masses only after midday, when the mountain breezes transport emissions from the adjacent valleys and plains to the top of the mountain. This results in clear diurnal patterns of both organic and inorganic concentrations. OA was also mainly composed (71%) of OOA, with contributions from HOA (5%) and biomass burning OA (BBOA; 24%). Moreover, in winter sporadic long-range transport from mainland Europe is observed. The results obtained in the present study highlight the importance of SOA formation processes at a remote site such as MSC, especially in summer. Additional research is needed to characterize the sources and processes of SOA formation at remote sites.

scholarly journals Air mass origins influencing TTL chemical composition over West Africa during 2006 summer monsoon

2010 ◽  
Vol 10 (22) ◽  
pp. 10753-10770 ◽  
Author(s):  
K. S. Law ◽  
F. Fierli ◽  
F. Cairo ◽  
H. Schlager ◽  
S. Borrmann ◽  
...  
Keyword(s):  
West Africa ◽  
Summer Monsoon ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Trace Gas ◽  
Air Mass ◽  
Back Trajectories ◽  
Air Masses

Abstract. Trace gas and aerosol data collected in the tropical tropopause layer (TTL) between 12–18.5 km by the M55 Geophysica aircraft as part of the SCOUT-AMMA campaign over West Africa during the summer monsoon in August 2006 have been analysed in terms of their air mass origins. Analysis of domain filling back trajectories arriving over West Africa, and in the specific region of the flights, showed that the M55 flights were generally representative of air masses arriving over West Africa during the first 2 weeks of August, 2006. Air originating from the mid-latitude lower stratosphere was under-sampled (in the mid-upper TTL) whilst air masses uplifted from central Africa (into the lower TTL) were over-sampled in the latter part of the campaign. Signatures of recent (previous 10 days) origins were superimposed on the large-scale westward flow over West Africa. In the lower TTL, air masses were impacted by recent local deep convection over Africa at the level of main convective outflow (350 K, 200 hPa) and on certain days up to 370 K (100 hPa). Estimates of the fraction of air masses influenced by local convection vary from 10 to 50% depending on the method applied and from day to day during the campaign. The analysis shows that flights on 7, 8 and 11 August were more influenced by local convection than on 4 and 13 August allowing separation of trace gas and aerosol measurements into "convective" and "non-convective" flights. Strong signatures, particularly in species with short lifetimes (relative to CO2) like CO, NO and fine-mode aerosols were seen during flights most influenced by convection up to 350–365 K. Observed profiles were also constantly perturbed by uplift (as high as 39%) of air masses from the mid to lower troposphere over Asia, India, and oceanic regions resulting in import of clean oceanic (e.g. O3-poor) or polluted air masses from Asia (high O3, CO, CO2) into West Africa. Thus, recent uplift of CO2 over Asia may contribute to the observed positive CO2 gradients in the TTL over West Africa. This suggests a more significant fraction of younger air masses in the TTL and needs to taken into consideration in derivations of mean age of air. Transport of air masses from the mid-latitude lower stratosphere had an impact from the mid-TTL upwards (20–40% above 370 K) during the campaign period importing air masses with high O3 and NOy. Ozone profiles show a less pronounced lower TTL minimum than observed previously by regular ozonesondes at other tropical locations. Concentrations are less than 100 ppbv in the lower TTL and vertical gradients less steep than in the upper TTL. The air mass origin analysis and simulations of in-situ net photochemical O3 production, initialised with observations, suggest that the lower TTL is significantly impacted by uplift of O3 precursors (over Africa and Asia) leading to positive production rates (up to 2 ppbv per day) in the lower and mid TTL even at moderate NOx levels. Photochemical O3 production increases with higher NOx and H2O in air masses with O3 less than 150 ppbv.

scholarly journals Long-term chemical characterization of tropical and marine aerosols at the Cape Verde Atmospheric Observatory (CVAO) from 2007 to 2011

2014 ◽  
Vol 14 (17) ◽  
pp. 8883-8904 ◽  
Author(s):  
K. W. Fomba ◽  
K. Müller ◽  
D. van Pinxteren ◽  
L. Poulain ◽  
M. van Pinxteren ◽  
...  
Keyword(s):  
Long Range ◽  
Mineral Dust ◽  
Chemical Characterization ◽  
Sea Salt ◽  
Saharan Dust ◽  
Long Range Transport ◽  
Air Mass ◽  
Aerosol Mass ◽  
Range Transport

Abstract. The first long-term aerosol sampling and chemical characterization results from measurements at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente are presented and are discussed with respect to air mass origin and seasonal trends. In total 671 samples were collected using a high-volume PM10 sampler on quartz fiber filters from January 2007 to December 2011. The samples were analyzed for their aerosol chemical composition, including their ionic and organic constituents. Back trajectory analyses showed that the aerosol at CVAO was strongly influenced by emissions from Europe and Africa, with the latter often responsible for high mineral dust loading. Sea salt and mineral dust dominated the aerosol mass and made up in total about 80% of the aerosol mass. The 5-year PM10 mean was 47.1 ± 55.5 μg m−2, while the mineral dust and sea salt means were 27.9 ± 48.7 and 11.1 ± 5.5 μg m−2, respectively. Non-sea-salt (nss) sulfate made up 62% of the total sulfate and originated from both long-range transport from Africa or Europe and marine sources. Strong seasonal variation was observed for the aerosol components. While nitrate showed no clear seasonal variation with an annual mean of 1.1 ± 0.6 μg m−3, the aerosol mass, OC (organic carbon) and EC (elemental carbon), showed strong winter maxima due to strong influence of African air mass inflow. Additionally during summer, elevated concentrations of OM were observed originating from marine emissions. A summer maximum was observed for non-sea-salt sulfate and was connected to periods when air mass inflow was predominantly of marine origin, indicating that marine biogenic emissions were a significant source. Ammonium showed a distinct maximum in spring and coincided with ocean surface water chlorophyll a concentrations. Good correlations were also observed between nss-sulfate and oxalate during the summer and winter seasons, indicating a likely photochemical in-cloud processing of the marine and anthropogenic precursors of these species. High temporal variability was observed in both chloride and bromide depletion, differing significantly within the seasons, air mass history and Saharan dust concentration. Chloride (bromide) depletion varied from 8.8 ± 8.5% (62 ± 42%) in Saharan-dust-dominated air mass to 30 \\textpm 12% (87 ± 11%) in polluted Europe air masses. During summer, bromide depletion often reached 100% in marine as well as in polluted continental samples. In addition to the influence of the aerosol acidic components, photochemistry was one of the main drivers of halogenide depletion during the summer; while during dust events, displacement reaction with nitric acid was found to be the dominant mechanism. Positive matrix factorization (PMF) analysis identified three major aerosol sources: sea salt, aged sea salt and long-range transport. The ionic budget was dominated by the first two of these factors, while the long-range transport factor could only account for about 14% of the total observed ionic mass.

scholarly journals Air mass origins influencing TTL chemical composition over West Africa during 2006 summer monsoon

2010 ◽  
Vol 10 (6) ◽  
pp. 15485-15536 ◽  
Author(s):  
K. S. Law ◽  
F. Fierli ◽  
F. Cairo ◽  
H. Schlager ◽  
S. Borrmann ◽  
...  
Keyword(s):  
West Africa ◽  
Summer Monsoon ◽  
Large Scale ◽  
Lower Stratosphere ◽  
Deep Convection ◽  
Lower Troposphere ◽  
Trace Gas ◽  
Air Mass ◽  
Back Trajectories ◽  
Air Masses

Abstract. Trace gas and aerosol data collected in the tropical tropopause layer (TTL) between 12–18.5 km by the M55 Geophysica aircraft as part of the SCOUT-AMMA campaign over West Africa during the summer monsoon in August 2006 have been analysed in terms of their air mass origins. Analysis of domain filling back trajectories arriving over West Africa, and in the specific region of the flights, showed that the M55 flights were generally representative of air masses arriving over West Africa during the first 2 weeks of August, 2006. Air originating from the mid-latitude lower stratosphere was under-sampled (in the mid-upper TTL) whilst air masses uplifted from central Africa (into the lower TTL) were over-sampled in the latter part of the campaign. Signatures of recent (previous 10 days) origins were superimposed on the large-scale westerly flow over West Africa. In the lower TTL, air masses were impacted by recent local deep convection over Africa at the level of main convective outflow (350 K, 200 hPa) and on certain days up to 370 K (100 hPa). Estimates of the fraction of air masses influenced by local convection vary from 10 to 50% depending on the method applied and from day to day during the campaign. The analysis shows that flights on 7, 8 and 11 August were more influenced by local convection than on 4 and 13 August allowing separation of trace gas and aerosol measurements into ''convective'' and ''non-convective'' flights. Strong signatures, particularly in short-lived species like CO, NO and fine-mode aerosols were seen during flights most influenced by convection up to 350–365 K. Observed profiles were also constantly perturbed by uplift (as high as 39%) of air masses from the mid to lower troposphere over Asia, India, and oceanic regions resulting in import of clean oceanic (e.g., O3-poor) or polluted air masses from Asia (high O3, CO, CO2) into West Africa. Thus, recent uplift of CO2 over Asia may contribute to the observed positive CO2 gradients in the TTL over West Africa. This suggests a more significant fraction of younger air masses in the TTL making it difficult to derive mean age of air from average gradients. Transport of air masses from the mid-latitude lower stratosphere had an impact from the mid-TTL upwards (20–40% above 370 K) during the campaign period importing air masses with high O3 and NOy. Ozone profiles show a less pronounced lower TTL minimum than observed previously by regular ozonesondes at other tropical locations. Concentrations are less than 100 ppbv in the lower TTL and vertical gradients less steep than in the upper TTL. The air mass origin analysis and simulations of in-situ net photochemical O3 production, initialised with observations, suggest that the lower TTL is significantly impacted by uplift of O3 precursors (over Africa and Asia) leading to positive production rates (up to 2 ppbv per day) in the lower and mid TTL even at moderate NOx levels. Photochemical O3 production increases with higher NOx and H2O in air masses with O3 less than 150 ppbv.

scholarly journals Long-term real-time chemical characterization of submicron aerosols at Montsec (Southern Pyrenees, 1570 m a.s.l.)

2014 ◽  
Vol 14 (21) ◽  
pp. 28809-28844 ◽  
Author(s):  
A. Ripoll ◽  
M. C. Minguillón ◽  
J. Pey ◽  
J. L. Jimenez ◽  
D. A. Day ◽  
...  
Keyword(s):  
Real Time ◽  
Long Range ◽  
Chemical Characterization ◽  
Western Mediterranean ◽  
Continuous Increase ◽  
Air Mass ◽  
Air Masses ◽  
Diurnal Patterns ◽  
Western Mediterranean Basin ◽  
Air Mass Origin

Abstract. Real-time measurements of inorganic (sulfate, nitrate, ammonium, chloride and black carbon (BC)) and organic submicron aerosols from a continental background site (Montsec, MSC, 1570 m a.s.l.) in the Western Mediterranean Basin (WMB) were conducted for 10 months (July 2011–April 2012). An Aerosol Chemical Speciation Monitor (ACSM) was co-located with other on-line and off-line PM1 measurements. Analyses of the hourly, diurnal, and seasonal variations are presented here, for the first time for this region. Seasonal trends in PM1 components are attributed to variations in: evolution of the planetary boundary layer (PBL) height, air mass origin, and meteorological conditions. In summer, the higher temperature and solar radiation increases convection, enhancing the growth of the PBL and the transport of anthropogenic pollutants towards high altitude sites. Furthermore, the regional recirculation of air masses over the WMB creates a continuous increase in the background concentrations of PM1 components and causes the formation of reserve strata at relatively high altitudes. Sporadically, MSC is affected by air masses from North Africa. The combination of all these atmospheric processes at local, regional and continental scales results in a high variability of PM1 components, with poorly defined daily patterns, except for the organic aerosols (OA). OA was mostly oxygenated organic aerosol (OOA), with two different types: semi-volatile (SV-OOA) and low-volatile (LV-OOA), and both showed marked diurnal cycles regardless of the air mass origin, especially SV-OOA. This different diurnal variation compared to inorganic aerosols suggested that OA components at MSC are not only associated with anthropogenic and long-range-transported secondary OA (SOA), but also with recently-produced biogenic SOA. Very different conditions drive the aerosol phenomenology in winter at MSC. The thermal inversions and the lower vertical development of the PBL leave MSC in the free troposphere most of the day, being affected by PBL air masses only after midday, when the mountain breezes transport emissions from the adjacent valleys and plains to the top of the mountain. This results in clear diurnal patterns of both organic and inorganic concentrations. Moreover, in winter sporadic long-range transport from mainland Europe is observed and leads to less marked diurnal patterns. The results obtained in the present study highlight the importance of SOA formation processes at a remote site such as MSC, especially in summer. Additional research is needed to characterize the sources of SOA at remote sites.

scholarly journals Particle characterization at the Cape Verde atmospheric observatory during the 2007 RHaMBLe intensive

2010 ◽  
Vol 10 (6) ◽  
pp. 2709-2721 ◽  
Author(s):  
K. Müller ◽  
S. Lehmann ◽  
D. van Pinxteren ◽  
T. Gnauk ◽  
N. Niedermeier ◽  
...  
Keyword(s):  
Marine Boundary Layer ◽  
Fine Particles ◽  
Mineral Dust ◽  
Sampling Site ◽  
Methanesulfonic Acid ◽  
Carbonaceous Material ◽  
Cape Verde ◽  
Sea Salt ◽  
Air Masses ◽  
Coarse Mode

Abstract. The chemical characterization of filter high volume (HV) and Berner impactor (BI) samples PM during RHaMBLe (Reactive Halogens in the Marine Boundary Layer) 2007 shows that the Cape Verde aerosol particles are mainly composed of sea salt, mineral dust and associated water. Minor components are nss-salts, OC and EC. The influence from the African continent on the aerosol constitution was generally small but air masses which came from south-western Europe crossing the Canary Islands transported dust to the sampling site together with other loadings. The mean mass concentration was determined for PM10 to 17 μg/m3 from impactor samples and to 24.2 μg/m3 from HV filter samples. Non sea salt (nss) components of PM were found in the submicron fractions and nitrate in the coarse mode fraction. Bromide was found in all samples with much depleted concentrations in the range 1–8 ng/m3 compared to fresh sea salt aerosol indicating intense atmospheric halogen chemistry. Loss of bromide by ozone reaction during long sampling time is supposed and resulted totally in 82±12% in coarse mode impactor samples and in filter samples in 88±6% bromide deficits. A chloride deficit was determined to 8% and 1% for the coarse mode particles (3.5–10 μm; 1.2–3.5 μm) and to 21% for filter samples. During 14 May with high mineral dust loads also the maximum of OC (1.71μg/m3) and EC (1.25 μg/m3) was measured. The minimum of TC (0.25 μg/m3) was detected during the period 25 to 27 May when pure marine air masses arrived. The concentrations of carbonaceous material decrease with increasing particle size from 60% for the ultra fine particles to 2.5% in coarse mode PM. Total iron (dust vs. non-dust: 0.53 vs. 0.06 μg m3), calcium (0.22 vs. 0.03 μg m3) and potassium (0.33 vs. 0.02 μg m3) were found as good indicators for dust periods because of their heavily increased concentration in the 1.2 to 3.5 μm fraction as compared to their concentration during the non-dust periods. For the organic constituents, oxalate (78–151 ng/m3) and methanesulfonic acid (MSA, 25–100 ng/m3) are the major compounds identified. A good correlation between nss-sulphate and MSA was found for the majority of days indicating active DMS chemistry and low anthropogenic influences.

scholarly journals Heat-Wave Events in Spain: Air Mass Analysis and Impacts on7Be Concentrations

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
M. A. Hernández-Ceballos ◽  
E. Brattich ◽  
G. Cinelli
Keyword(s):  
Heat Wave ◽  
Simultaneous Occurrence ◽  
Mass Analysis ◽  
Air Mass ◽  
Air Masses ◽  
Backward Trajectories ◽  
Activity Concentrations ◽  
Mass Circulation ◽  
The Impact

The present paper describes and characterizes the air mass circulation during the heat-wave events registered during the period 2005–2014 over Spain, paying special attention to the role of the Saharan circulations. Backward trajectories at 500, 1500, and 3000 m in Seville (south), Madrid (centre), and Bilbao (north) during the thirteen heat-wave events identified are analysed. Finally, the impact of the heat-wave events and of each advection pattern on7Be activity concentrations is also analysed. The heat-wave events are characterized roughly by western, southern, and nearby advections, with a higher frequency of the first two types. The analysis shows an increase of African air masses with height, presenting a different spatial impact over Spain, with a decreasing occurrence and a decrease in the simultaneous occurrence percentage from south to north. On average, the7Be activity concentrations during these events show an increase of concentrations in central (21%) and southern (18%) areas and a decrease in northern (13%) Spain. This increase is not associated with Saharan air masses but instead with the arrival of distant westerly air masses.

scholarly journals Long-term chemical characterization of tropical and marine aerosols at the CVAO: field studies (2007 to 2011)

2014 ◽  
Vol 14 (3) ◽  
pp. 3917-3971 ◽  
Author(s):  
K. W. Fomba ◽  
K. Müller ◽  
D. van Pinxteren ◽  
L. Poulain ◽  
M. van Pinxteren ◽  
...  
Keyword(s):  
Long Range ◽  
Mineral Dust ◽  
Chemical Characterization ◽  
Sea Salt ◽  
Saharan Dust ◽  
Long Range Transport ◽  
Air Mass ◽  
Aerosol Mass ◽  
Range Transport

Abstract. The first long-term aerosol sampling and chemical characterization results from measurements at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente are presented and are discussed with respect to air mass origin and seasonal trends. In total 671 samples were collected using a high volume PM10 sampler on quartz fiber filters from January 2007 to December 2011. The samples were analyzed for their aerosol chemical composition including their ionic and organic constituents. Back trajectory analyses showed that the aerosol at CVAO was strongly influenced by emissions from Europe and Africa with the later often responsible for high mineral dust loading. Sea salt and mineral dust dominated the aerosol mass and made up in total about 80% of the aerosol mass. The 5 yr PM10 mean was 47.1 ± 55.5 μg m−3 while the mineral dust and sea salt means were 27.9 ± 48.7 μg m−3 and 11.1 ± 5.5 μg m−3, respectively. Non-sea-salt (nss) sulfate made up 62% of the total sulfate and originated from both long range transport from Africa or Europe and marine sources. Strong seasonal variation was observed for the aerosol components. While nitrate showed no clear seasonal variation with an annual mean of 1.1 ± 0.6 μg m−3, the aerosol mass, OC and EC, showed strong winter maxima due to strong influence of African air mass inflow. Additionally during summer, elevated concentrations of OM were observed originating from marine emissions. A summer maximum was observed for non-sea-salt sulfate and was connected to periods where air mass inflow was predominantly of marine origin indicating that marine biogenic emissions were a significant source. Ammonium showed distinct maximum in spring and good correlation with ocean surface water chlorophyll a concentrations. Good correlations were also observed between nss-sulfate and oxalate during the summer and winter seasons indicating a likely photochemical in-cloud processing of the marine and anthropogenic precursors of these species. High temporal variability was observed in both chloride and bromide depletion differing significantly within the seasons, air mass history and Saharan dust concentration. Chloride (bromide) depletion varied from 8.8 ± 8.5% (62 ± 42%) in Saharan dust dominated air mass to 30 ± 12% (87 ± 11%) in polluted Europe air masses. During summer, bromide depletion often reached 100% in pure marine as well as in polluted continental samples. In addition to the influence of the aerosol acidic components, photochemistry was one of the main drivers of halogenide depletion during the summer while during dust events, displacement reaction with nitric acid was found to be the dominant mechanism. PMF analysis identified three major aerosol sources including sea salt, aged sea salt and long range transport. The ionic budget was dominated by the first two of these factors while the long range transport factor could only account for about 14% of the total observed ionic mass.

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