Investigation of nucleation events vertical extent: a long term study at two different altitude sites

Abstract

Abstract. In this work we present an analysis of the occurrence of nucleation events during more than three years of measurements at two different rural altitude sites, the puy de Dôme research station (1465 m a.s.l.) and the Opme station (660 m a.s.l.), central France. The collected database is a unique combination of scanning mobility particle sizer (10-400 nm), air ion spectrometers (from 0.8 to 42 nm for NTP-conditions), and, neutral clusters and air ion spectrometers (from 0.8 to 42 nm for NTP-conditions) measurements at these two different altitudes nearly located research stations, from February 2007 to June 2010. The seasonality of the frequency of nucleation events was studied at the puy de Dôme station and maximum of events frequency was found during early spring and early autumn. During the measurement period, neither the particle formation rates (J 2 = 1.382 ± 0.195 s −1 ) nor the growth rates (ḠR 1.3−20 nm = 6.20 ± 0.12 nm h −1 ) differ from one site to the other on average. Hovewer, we found that, on 437 sampling days in common to the two sites, the nucleation frequency was higher at the puy de Dôme station (35.9 %, 157 days) than at the low elevation station of Opme (20.8 %, 91 days). LIDAR measurements and the evolution of the potential equivalent temperature revealed that the nucleation could be triggered either (i) within the whole low tropospheric column at the same time from the planetary boundary layer to the top of the interface layer (29.2 %, 47 events), (ii) above the planetary boundary layer upper limit (43.5 %, 70 events), and (iii) at low altitude and then transported, conserving dynamic and properties, at high altitude (24.8 %, 40 events). This is the first time that the vertical extent of nucleation can be studied over a long observational period, allowing for a rigorous statistical analysis of the occurrence of nucleation over the whole lower troposphere. This work Correspondence to: J. Boulon (j.boulon@opgc.univ-bpclermont.fr) highlights the fact that nucleation can occur over a large vertical extent, at least the whole low tropospheric column, and also the fact that it occurs twice as frequently as actually detected in the planetary boundary layer. The role of sulfuric acid and ions in the nucleation process was investigated at the altitude station and no correlation was found between nucleation events and the estimated sulfuric acid concentrations. However, the contribution of ion-induced nucleation was found to be relatively high (12.49 ± 2.03 % of the total nucleation rate).

General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

“…This is observed at mountain stations (Venzac et al, 2009;Boulon et al, 2011) but also during airborne measurements above central Europe (Crumeyrolle et al, 2010). This is clearly an additional source of small particles to the FT.…”

Airborne measurements of new particle formation in the free troposphere above the Mediterranean Sea during the HYMEX campaign

“…These first observations suggest that higher nucleation frequencies found above 2000 m could be, at least partly, explained by lower CS. The fact that nucleation could be promoted at higher altitudes due to lower CS values was also reported by Boulon et al (2011) A more complete analysis focussed on altitudes above 2000 m was then conducted to highlight the role of the CS in the nucleation process at higher altitudes. Figure 9 shows the correlation between N 5-10 particle concentration and CS, separately for the two altitude ranges above 2000 m. The N 5-10 concentrations shown are 130 s averaged values coinciding with SMPS measurements used for the CS calculation.…”

“…O'Dowd et al, 1998O'Dowd et al, , 2002. NPF events' characteristics, such as spatial extent, both vertical and horizontal (Crumeyrolle et al, 2010;Boulon et al, 2011), particle formation and growth rates Yli-Juuti et al, 2011), are known to be affected by atmospheric parameters, including the number of gaseous precursors, the concentration of pre-existing aerosol particles, and meteorological variables (temperature, relative humidity, solar radiation). However, current knowledge of the theory that lies beyond NPF remains poor, especially at high altitudes, i.e.…”

Three years of semicontinuous greenhouse gas measurements at the Puy de Dôme station (central France)

“…On both maps, the station is located within the black grid cell. By analyzing back trajectories from HYSPLIT over 437 days at Puy de Dôme (i.e., from Atlantic and continental western Europe areas), Boulon et al (2011) showed that 87 % of air masses reaching the station are from the west. A statistical analysis of back trajectories over 4 years conducted by Venzac et al (2009) demonstrated that winter air masses reaching Puy de Dôme travel over longer distances from the west than summer air masses.…”

“…The Puy de Dôme station also participates in the "Cucumbers comparison programme" (http://cucumbers. uea.ac.uk/) in the framework of the European Union CarboEurope project (2000)(2001)(2002)(2003)(2004)(2005), EU IMECC (2007-2011 and InGOS (2011InGOS ( -2015 infrastructure projects. Three cylinders are alternately analyzed on the GC at Puy de Dôme and at the Gif-sur-Yvette, Trainou (France), Kasprowy Wierch (Poland) and Hegyhatsal (Hungary) stations.…”