Spatial extension of nucleating air masses in the Carpathian Basin

Abstract

Abstract. Particle number size distributions were measured by differential mobility particle sizer in the diameter range of 6-1000 nm in the near-city background and city centre of Budapest continuously for two years. The city is situated in the middle part of the Carpathian Basin, which is a topographically discrete unit in the southeastern part of central Europe. Yearly mean nucleation frequencies and uncertainties for the near-city background and city centre were (28 + 6/−4) % and (27 + 9/−4) %, respectively. The total numbers of days with continuous and uninterrupted growth process were 43 and 31, respectively. These events and their properties were utilised to investigate the spatial scale of the nucleation in the basin, and whether there are any specific trajectories for the nucleating air masses. Local wind speed and direction data indicated that there seem to be differences between the nucleation and growth intervals and non-nucleation days. For further analysis, backward trajectories were generated by a simple air parcel trajectory model. Start and end time parameters of the nucleation and an end time parameter of the particle growth were derived by a standardised procedure based on examining the channel contents of the contour plots. These parameters were used to specify a segment on each backward trajectory that is associated with the nucleating air mass. The results indicated that regional nucleation happened in the continental boundary layer mostly in the Carpathian Basin but that the most distant trajectories originated outside of the basin. The nucleating air masses were predominantly associated with NW and SE geographical sectors, and some of them were also related to larger forested territories. The results also emphasised indirectly that the regional new particle formation and growth phenomena observable at the fixed location often expand to the bulk of the Carpathian Basin.

Regional effect on urban atmospheric nucleation

“…It is worth mentioning that J d depends implicitly on GR. The earliest estimated time of the beginning of nucleation (t 1 ), the latest estimated time of the beginning of nucleation (t 2 ) and the ending time of the particle growth process (t e ) were derived by a comparative method (Németh and Salma, 2014). The time t 1 also includes the time shift that accounts for the particle growth from the stable neutral cluster mode at 1.5 ± 0.4 nm (Kulmala et al, 2007) to the smallest detectable diameter limit of the DMPS systems by adopting the GR value in the size window nearest to it in size space.…”

Atmospheric new particle formation and growth: review of field observations

“…For this purpose, various methods based on single-site measurements have been developed (e.g. Birmili et al 2003, Hussein et al 2009, Crippa and Pryor 2013, Kristensson et al 2014, Nemeth and Salma 2014. A more detailed view on the spatial extent and variability of NPF can be obtained by using simultaneous measurements from two or more stations, and such analyses have been performed for Northern ( (Shen et al 2018).…”

Spatial distribution and occurrence probability of regional new particle formation events in eastern China

“…It is based on PNSD measurement data and back trajectories and has been validated using the Finnish field site Hyytiälä as a test station (Kristensson et al, 2014). It has further been used at a European continental site, Budapest, Hungary (Németh and Salma, 2014). The NanoMap method follows four steps: (1) classification of NPF events and identification of class 1 events , (2) determination of the start and end time of the particle formation at the lowest size bin of the measured PNSD, (3) estimation of the time when the newly formed particle mode can no longer be identified (end of growth time is referred to as EOG time), and (4) the plotting of a geographical map with the spatial distribution of NPF events based on the above defined time points and air mass back trajectories.…”

“…Birmili et al, 2003;Komppula et al, 2006;Charron et al, 2007;Hussein et al, 2009;Németh and Salma, 2014;Väänänen et al, 2016) in which the horizontal scale of NPF has been found to be from hundreds to thousands of kilometres. Many of these studies have used one or several measurement sites as the bases of their analysis.…”

“…Many of these studies have used one or several measurement sites as the bases of their analysis. Some of them were conducted based on stationary measurements at more than one ground-level station simultaneously (Hussein et al, 2009;Németh and Salma, 2014;Komppula et al, 2006), and some of them used sites at different altitudes in the same area (Boulon et al, 2011;Birmili et al, 2003). There have also been airborne measurements on the spatial scale of NPF events (Väänänen et al, 2016).…”