5 research outputs found
Aerosol number fluxes and concentrations over a southern European urban area
Although cities are an important source of aerosol particles, aerosol number flux measurements over urban areas are scarce. These measurements are however important as they can allow us to identify the different sources/sinks of aerosol particles and quantify their emission contributions. Therefore, they can help us to understand the aerosol impacts on human health and climate, and to design effective mitigation strategies through the reduction of urban aerosol emissions. In this work we analyze the aerosol number concentrations and fluxes for particles with diameters larger than 2.5 nm measured by eddy covariance technique at an urban area (Granada city, Spain) from November 2016 to April 2018. This is the first study of particle number flux in an urban area in the Iberian Peninsula and is one of the few current studies that report long-term aerosol number flux measurements. The results suggest that, on average, Granada urban area acted as a net source for atmospheric aerosol particles with median particle number flux of 150 x 10(6) m(-2) s(-1). Downward negative fluxes were observed in only 12% of the analyzed data, and most of them were observed during high aerosol load conditions. Both aerosol number fluxes and concentrations were maximum in winter and 50% larger than those measured in summer due to the increased emissions from domestic heating, burning of residual agricultural waste in the agricultural area surrounding the site, as well as to the lower aerosol dilution effects during winter. The analysis of the seasonal diurnal variability of the aerosol number concentration revealed the significant impact of traffic emissions on aerosol population over Granada urban area in all seasons. It also shows the impact of domestic heating and agricultural waste burning emissions in winter as well as the influence of new particle formation processes in summer and spring seasons. Closer analysis by wind sector demonstrated that both aerosol concentrations and fluxes from urban sector (where high density of anthropogenic sources is located) were lower than those from rural sector (which includes agricultural area but also the main highway of the city). This evidences the strong impact of aerosol emissions from traffic circulating on the highway on aerosol population over our measurement site.Peer reviewe
Monumental heritage exposure to urban black carbon pollution
In this study, aerosol light-absorption measurements obtained at three sites during a winter campaign were used to analyse and identify the major sources of Black Carbon (BC) particles in and around the Alhambra monument, a UNESCO World Heritage Site that receives over 2 million visitors per year. The Conditional Bivariate Probability Function and the Aethalometer model were employed to identify the main sources of BC particles and to estimate the contributions of biomass burning and fossil fuel emissions to the total Equivalent Black Carbon (EBC) concentrations over the monumental complex. Unexpected high levels of EBC were found at the Alhambra, comparable to those measured in relatively polluted European urban areas during winter. EBC concentrations above 3.0 μg/m3, which are associated with unacceptable levels of soiling and negative public reactions, were observed at Alhambra monument on 13 days from 12 October 2015 to 29 February 2016, which can pose a risk to its long-term conservation and may cause negative social and economic impacts. It was found that road traffic emissions from the nearby urban area and access road to the Alhambra were the main sources of BC particles over the monument. However, biomass burning emissions were found to have very small impact on EBC concentrations at the Alhambra. The highest EBC concentrations were observed during an extended stagnant episode associated with persistent high-pressure systems, reflecting the large impact that can have these synoptic conditions on BC over the Alhambra.European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 654109, ACTRIS-2.Spanish Ministry of Economy and Competitiveness and FEDER through project CGL2013-45410-R, CGL2016-81092-R 598 and CGL2012-30729.Andalusia Regional Government through project P12- RNM-2409 and P12-FQM-1889
ON THE POSSIBLE CONNECTION BETWEEN AFRICAN DUST OUTBREAKS AND STRATOSPHERE-TO-TROPOSPHERE EXCHANGE AS MEASURED IN THE IBERIAN PENINSULA
The FRESA (\u201cImpacto de las intrusiones de masas de aire
con polvo aFRicano y de masas de aire EStratosf\ue9rico en
la Pen\uednsula Ib\ue9rica. Influencia de El Atlas\u201d) Spanish
national project aims to study the interaction between
upper level disturbances and the Atlas Mountains in
promoting low-level instability and cyclone formation in
the lee of the Atlas Mountains, responsible of dust uplift
over the Sahara Desert and also of upper tropospherelower
stratosphere (UT-LS) to troposphere transport.
This work presents an overview of the results obtained
during a preliminary campaign of the FRESA project
(June-October 2016) at Sierra Nevada (Granada)
(37.096 N, 3.387 W, 2550 m a.s.l.) analysing weekly
samples of 7Be, 210Pb (tracers of UTLS and continental
origin, respectively) and PM10, as well as hourly particle
number size distribution from a Grimm OPC. 96-hour 3D
backward trajectories starting every 6 h (00, 06, 12, and
18Z) were calculated using the HYSPLIT4 model with the
meteorological input from the ERA-Interim 0.5 deg
meteorological dataset. Moreover, potential vorticity
(PV) data was associated to each of the 96 trajectory
endpoints by performing a 3D nearest-neighbour
interpolation to the 27 isobaric levels between 100 and
1000 hPa of the ERA-Interim reanalysis.
During this pre-campaign, 12 Saharan dust and 14
stratospheric intrusions days were identified analysing
back-trajectories, BSC-DREAM model, particle number
concentrations and synoptic charts: the meteorological
situation leading to these outbreaks will be further
studied in detail. The analysis of the source-receptor
relationship for 7
Be, 210Pb and PM10 shows the influence
of the Sahara Desert and of air parcels which passed over
the North Sea with strong subsidence and then at lower
heights over the western Mediterranean basin on all the
three parameters. The analysis also shows that the
Atlantic air masses are more associated to 7
Be than 210Pb
increases. The fine and coarse fractions (smaller and
larger than 1 \ub5m in diameter) were analysed on both a
weekly and 6-hourly basis. Locations to the south of the
Atlas and the western Mediterranean were identified as
important sources of the coarse fraction while the origin
of the fine fraction was quite similar to that of 7
Be,
probably because of the attachment of 7
Be nuclide to
accumulation-mode aerosols soon after its production.
The comparison between 7
Be/210Pb potential sources
with those of high PV crossing shows that the Atlas is
connected both to events of high PV values and to a
strong PSCF probability of the 7
Be/210Pb ratio. This result
suggests that the high PV areas located around the Atlas
Mountains are not linked to friction and turbulence over
the mountains themselves, but are rather associated to
tropopause crossing and Stratosphere-TroposphereExchange
(STE) occurring in the leeward side of mountain
ranges, in agreement with the recent work of Brattich et
al. (submitted).
This work was supported by the Spanish MINECO under
grant CGL2015-70741-R (FRESA).
Brattich et al. (submitted to JGR), Influence of
stratospheric air masses on radiotracers and ozone
over the central Mediterranean
ON THE POSSIBLE CONNECTION BETWEEN AFRICAN DUST OUTBREAKS AND STRATOSPHERE-TO-TROPOSPHERE EXCHANGE AS MEASURED IN THE IBERIAN PENINSULA
The FRESA (\u201cImpacto de las intrusiones de masas de aire
con polvo aFRicano y de masas de aire EStratosf\ue9rico en
la Pen\uednsula Ib\ue9rica. Influencia de El Atlas\u201d) Spanish
national project aims to study the interaction between
upper level disturbances and the Atlas Mountains in
promoting low-level instability and cyclone formation in
the lee of the Atlas Mountains, responsible of dust uplift
over the Sahara Desert and also of upper tropospherelower
stratosphere (UT-LS) to troposphere transport.
This work presents an overview of the results obtained
during a preliminary campaign of the FRESA project
(June-October 2016) at Sierra Nevada (Granada)
(37.096 N, 3.387 W, 2550 m a.s.l.) analysing weekly
samples of 7Be, 210Pb (tracers of UTLS and continental
origin, respectively) and PM10, as well as hourly particle
number size distribution from a Grimm OPC. 96-hour 3D
backward trajectories starting every 6 h (00, 06, 12, and
18Z) were calculated using the HYSPLIT4 model with the
meteorological input from the ERA-Interim 0.5 deg
meteorological dataset. Moreover, potential vorticity
(PV) data was associated to each of the 96 trajectory
endpoints by performing a 3D nearest-neighbour
interpolation to the 27 isobaric levels between 100 and
1000 hPa of the ERA-Interim reanalysis.
During this pre-campaign, 12 Saharan dust and 14
stratospheric intrusions days were identified analysing
back-trajectories, BSC-DREAM model, particle number
concentrations and synoptic charts: the meteorological
situation leading to these outbreaks will be further
studied in detail. The analysis of the source-receptor
relationship for 7
Be, 210Pb and PM10 shows the influence
of the Sahara Desert and of air parcels which passed over
the North Sea with strong subsidence and then at lower
heights over the western Mediterranean basin on all the
three parameters. The analysis also shows that the
Atlantic air masses are more associated to 7
Be than 210Pb
increases. The fine and coarse fractions (smaller and
larger than 1 \ub5m in diameter) were analysed on both a
weekly and 6-hourly basis. Locations to the south of the
Atlas and the western Mediterranean were identified as
important sources of the coarse fraction while the origin
of the fine fraction was quite similar to that of 7
Be,
probably because of the attachment of 7
Be nuclide to
accumulation-mode aerosols soon after its production.
The comparison between 7
Be/210Pb potential sources
with those of high PV crossing shows that the Atlas is
connected both to events of high PV values and to a
strong PSCF probability of the 7
Be/210Pb ratio. This result
suggests that the high PV areas located around the Atlas
Mountains are not linked to friction and turbulence over
the mountains themselves, but are rather associated to
tropopause crossing and Stratosphere-TroposphereExchange
(STE) occurring in the leeward side of mountain
ranges, in agreement with the recent work of Brattich et
al. (submitted).
This work was supported by the Spanish MINECO under
grant CGL2015-70741-R (FRESA).
Brattich et al. (submitted to JGR), Influence of
stratospheric air masses on radiotracers and ozone
over the central Mediterranean