English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Particle number concentration and size distribution are important variablesneeded to constrain the role of atmospheric particles in the Earth radiationbudget, both directly and indirectly through CCN activation. They are alsolinked to regulated variables such as particle mass (PM) and therefore ofinterest to air quality studies. However, data on their long-termvariability are scarce, in particular at high altitudes. In this paper, weinvestigate the diurnal and seasonal variability of the aerosol total numberconcentration and size distribution at the puy de Dôme research station(France, 1465 m a.s.l.). We report a variability of aerosol particle totalnumber concentration measured over a five-year (2003–2007) period forparticles larger than 10 nm and aerosol size distributions between 10 and500 nm over a two-year period (January 2006 to December 2007).Concentrations show a strong seasonality with maxima during summer andminima during winter. A diurnal variation is also observed with maximabetween 12:00 and 18:00 UTC. At night (00:00–06:00 UTC), the median hourlytotal concentration varies from 600 to 800 cm−3 during winter and from1700 to 2200 cm−3 during summer. During the day (08:00–18:00 UTC), theconcentration is in the range of 700 to 1400 cm−3 during winter and of2500 to 3500 cm−3 during summer. An averaged size distribution ofparticles (10–500 nm) was calculated for each season. The total aerosolnumber concentrations are dominated by the Aitken mode integralconcentrations, which drive most of the winter to summer totalconcentrations increase. The night to day increase in dominated by thenucleation mode integral number concentration. Because the site is locatedin the free troposphere only a fraction of the time, in particular at nightand during the winter season, we have subsequently analyzed the variabilityfor nighttime and free tropospheric (FT)/residual layer (RL) conditionsonly. We show that a seasonal variability is still observed for these FT/RLconditions. The FT/RL seasonal variation is due to both seasonal changes inthe air mass origin from winter to summer and enhanced concentrations ofparticles in the residual layer/free troposphere in summer. The laterobservation can be explained by higher emissions intensity in the boundarylayer, stronger exchanges between the boundary layer and the freetroposphere as well as enhanced photochemical processes. Finally, aerosolsmean size distributions are calculated for a given air mass type(marine/continental/regional) according to the season for the specificconditions of the residual layer/free troposphere. The seasonal variabilityin aerosol sources seems to be predominant over the continent compared tothe seasonal variation of marine aerosol sources. These results are ofregional relevance and can be used to constrain chemical-transport modelsover Western Europe

Seasonal variation of aerosol size distributions in the free troposphere and residual layer at the puy de Dôme station, France