Temporal variability of summer‐time ozone and aerosols in the free troposphere over the eastern North Atlantic

Prospero, Joseph M.; Schmitt, R.; Cuevas, E.; Savoie, Dennis L.; Graustein, W. C.; Turekian, Karl K.; Volz‐Thomas, A.; Díaz, A. M.; Oltmans, S. J.; Levy, H.

doi:10.1029/95gl02791

Cited by 108 publications

(69 citation statements)

References 21 publications

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“…28,29 However, a study in Vienna gave results similar to those for Waddell and Deer Park; that is, very poor correlations were obtained between surface O 3 and 7 Be, with R 2 values consistently below 0.2. 17 It was concluded that although elevated levels of 7 Be (5-12 mBq m Ϫ3 ) were observed, indicating possible transport from aloft, any accompanying O 3 was destroyed quickly at or near ground level.…”

Section: Resultsmentioning

confidence: 84%

“…Thus, quantifying the 7 Be content in fine aerosols can give a measure of the transport of this fine aerosol material from the upper troposphere/lower stratosphere to the surface where it is sampled. Past work has suggested that this might be a useful way to determine stratospheric intrusions into the lower atmosphere and also to estimate the maximum extent to which stratospheric O 3 is affecting tropospheric sites during tropopause folding events, 9,[15][16][17][18][19][20][21]28,29 generally associated with intense storm events and frontal movements in the midlatitude northern hemisphere.…”

Section: Introductionmentioning

confidence: 99%

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Beryllium-7 Measurements in the Houston and Phoenix Urban Areas: An Estimation of Upper Atmospheric Ozone Contributions

Gaffney

Marley

Cunningham

et al. 2005

Journal of the Air & Waste Management Association

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Section: Resultsmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Beryllium-7 Measurements in the Houston and Phoenix Urban Areas: An Estimation of Upper Atmospheric Ozone Contributions

Gaffney

Marley

Cunningham

et al. 2005

Journal of the Air & Waste Management Association

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“…The 7 Be radiotracer (half-life 53.3 days) is produced by cosmic ray spallation reactions with nitrogen and oxygen in the stratosphere and upper troposphere (Viezee and Singh, 1980). The 7 Be and 210 Pb radionuclides were measured at IZO on a daily basis within the AEROCE (AEROsol Ocean chemistry Experiment) project (Prospero et al, 1995) in the period of 1989-1991 as tracers for UTLS and CBL air, respectively.…”

Section: Be and 210 Pb Radiotracersmentioning

confidence: 99%

Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

et al. 2013

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Abstract. An analysis of the 22-yr ozone (O3) series (1988–2009) at the subtropical high mountain Izaña~station (IZO; 2373 m a.s.l.), representative of free troposphere (FT) conditions, is presented. Diurnal and seasonal O3 variations as well as the O3 trend (0.19 ± 0.05 % yr−1 or 0.09 ppbv yr−1), are assessed. A climatology of O3 transport pathways using backward trajectories shows that higher O3 values are associated with air masses travelling above 4 km altitude from North America and North Atlantic Ocean, while low O3 is transported from the Saharan continental boundary layer (CBL). O3 data have been compared with PM10, 210Pb, 7Be, potential vorticity (PV) and carbon monoxide (CO). A clear negative logarithmic relationship was observed between PM10 and surface O3 for all seasons. A similar relationship was found between O3 and 210Pb. The highest daily O3 values (90th percentile) are observed in spring and in the first half of summer time. A positive correlation between O3 and PV, and between O3 and 7Be is found throughout the year, indicating that relatively high surface O3 values at IZO originate from the middle and upper troposphere. We find a good correlation between O3 and CO in winter, supporting the hypothesis of long-range transport of photochemically generated O3 from North America. Aged air masses, in combination with sporadic inputs from the upper troposphere, are observed in spring, summer and autumn. In summer time high O3 values seem to be the result of stratosphere-to-troposphere (STT) exchange processes in regions neighbouring the Canary Islands. Since 1995–1996, the North Atlantic Oscillation has changed from a predominantly high positive phase to alternating between negative, neutral or positive phases. This change results in an increased flow of the westerlies in the mid-latitude and subtropical North Atlantic, thus favouring the transport of O3 and its precursors from North America, and a higher frequency of storms over North Atlantic, with a likely higher incidence of STT processes in mid-latitudes. These processes lead to an increase of tropospheric O3 in the subtropical North Atlantic region after 1996 that has been reflected in surface O3 records at IZO.

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“…In particular, those mineral aerosol particles, which are characterised by very large surface area, can strongly absorb the shortwave solar radiation, influencing the radiative forcing of climate (Dickerson et al, 1997), or causing a photolysis rate reduction, thus inhibiting ozone production. In fact, in the lower atmosphere, mineral aerosol may strongly influence the balance of atmospheric trace gases, including ozone (Prospero et al, 1995;Dentener and Crutzen, 1993;Zhang et al, 1994;Dickerson et al, 1997). Dentener et al (1996) in their modelling studies, suggested that the ozone destruction on mineral aerosol surfaces could lead to a 10% reduction of O 3 concentrations in the dust source areas.…”

Section: Introductionmentioning

confidence: 99%

“…On the contrary, under southerly winds coming from the desert, very low O 3 concentrations with a diurnal variation between 25 and 45 ppbv were measured (Gusten et al, 1996). Outside the African deserts, but close to the west coast of north Africa, trace gas measurements, carried out at the Izaña baseline mountain station (Canary Islands), showed marked surface ozone depletions during Saharan dust events (Prospero et al, 1995;Schmitt et al, 1998), which significantly influenced the annual mean ozone concentrations (Schmitt et al, 1998;de Reus et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Aerosol-ozone correlations during dust transport episodes

Bonasoni

Cristofanelli²,

Calzolari³

et al. 2004

Atmos. Chem. Phys.

132

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Abstract. Its location in the Mediterranean region and its physical characteristics render Mt. Cimone (44 • 11 N, 10 • 42 E), the highest peak of the Italian northern Apennines (2165 m asl), particularly suitable to study the transport of air masses from the north African desert area to Europe. During these northward transports 12 dust events were registered in measurements of the aerosol concentration at the station during the period June-December 2000, allowing the study of the impact of mineral dust transports on free tropospheric ozone concentrations, which were also measured at Mt. Cimone. Three-dimensional backward trajectories were used to determine the air mass origin, while TOMS Aerosol Index data for the Mt. Cimone area were used to confirm the presence of absorbing aerosol over the measurement site.A trajectory statistical analysis allowed identifying the main source areas of ozone and aerosols. The analysis of these back trajectories showed that central Europe and north and central Italy are the major pollution source areas for ozone and fine aerosol, whereas the north African desert regions were the most important source areas for coarse aerosol and low ozone concentrations. During dust events, the Mt. Cimone mean volume concentration for coarse particles was 6.18 µm 3 /cm 3 compared to 0.63 µm 3 /cm 3 in dust-free conditions, while the ozone concentrations were 4% to 21% lower than the monthly mean background values. Our observations show that surface ozone concentrations were lower than the background values in air masses coming from north Africa, and when these air masses were also rich in coarse particles, the lowest ozone values were registered. Moreover, preliminary results on the possible impact of the dust events on PM 10 and ozone values measured in Italian urbanCorrespondence to: P. Bonasoni (p.bonasoni@isac.cnr.it) and rural areas showed that during the greater number of the considered dust events, significant PM 10 increases and ozone decreases have occurred in the Po valley.

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Temporal variability of summer‐time ozone and aerosols in the free troposphere over the eastern North Atlantic

Cited by 108 publications

References 21 publications

Beryllium-7 Measurements in the Houston and Phoenix Urban Areas: An Estimation of Upper Atmospheric Ozone Contributions

Beryllium-7 Measurements in the Houston and Phoenix Urban Areas: An Estimation of Upper Atmospheric Ozone Contributions

Assessment of atmospheric processes driving ozone variations in the subtropical North Atlantic free troposphere

Aerosol-ozone correlations during dust transport episodes

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