One year boundary layer aerosol size distribution data from five nordic background stations

Size distribution measurements performed at five different stations have been investigated during a one-year period between 01 June 2000 and 31 May 2001 with focus on diurnal, seasonal and geographical differences of size distribution properties. The stations involved cover a large geographical area ranging from the Finnish Lapland (67o N) down to southern Sweden (56o N) in the order Varrio, Pallas, Hyytiala, Aspvreten and Vavihill. The shape of the size distribution is typically bimodal during winter with a larger fraction of accumulation mode particles compared to the other seasons. Highest Aitken mode concentration is found during summer and spring during the year of study. The maximum of nucleation events occur during the spring months at all stations. Nucleation events occur during other months as well, although not as frequently. Large differences were found between different categories of stations. Northerly located stations such as Pallas and Varrio presented well-separated Aitken and accumulation modes, while the two modes often overlap significantly at the two southernmost stations Vavihill and Aspvreten. A method to cluster trajectories was used to analyse the impact of long-range transport on the observed aerosol properties. Clusters of trajectories arriving from the continent were clearly associated with size distributions shifted towards the accumulation mode. This feature was more pronounced the further south the station was located. Marine- or Arctic-type clusters were associated with large variability in the nuclei size ranges. A quasi-lagrangian approach was used to investigate transport related changes in the aerosol properties. Typically, an increase in especially Aitken mode concentrations was observed when advection from the north occurs, i.e. allowing more continental influence on the aerosol when comparing the different measurement sites. When trajectory clusters arrive to the stations from SW, a gradual decrease in number concentration is experienced in all modes as latitude of measurement site increases.

[1]  S. Solberg,et al.  Atmospheric Chemistry and Physics , 2002 .

[2]  Alfred Wiedensohler,et al.  Atmospheric particle number size distribution in central Europe: Statistical relations to air masses and meteorology , 2001 .

[3]  L. Pirjola,et al.  How significantly does coagulational scavenging limit atmospheric particle production , 2001 .

[4]  M. Kulmala,et al.  Mid-latitude North-Atlantic aerosol characteristics in clean and polluted air , 2001 .

[5]  Ü. Rannik,et al.  Overview of the international project on biogenic aerosol formation in the boreal forest (BIOFOR) , 2001 .

[6]  M. Boy,et al.  Effects of air masses and synoptic weather on aerosol formation in the continental boundary layer , 2001 .

[7]  H. Hansson,et al.  Biogenic emissions and gaseous precursors to forest aerosols , 2001 .

[8]  Ü. Rannik,et al.  Effects of continental boundary layer evolution, convection, turbulence and entrainment, on aerosol formation , 2001 .

[9]  C. O'Dowd,et al.  Physical characterization of aerosol particles during nucleation events , 2001 .

[10]  A. Wiedensohler,et al.  New particle formation in the continental boundary layer: Meteorological and gas phase parameter influence , 2000 .

[11]  N Künzli,et al.  Public-health impact of outdoor and traffic-related air pollution: a European assessment , 2000, The Lancet.

[12]  L. Pirjola,et al.  The effect of atmospheric waves on aerosol nucleation and size distribution , 2000 .

[13]  Pasi Aalto,et al.  One-Year Data of Submicron Size Modes of Tropospheric Background Aerosol in Southern Finland , 2000 .

[14]  Kaarle Hämeri,et al.  Effects of meteorological processes on aerosol particle size distribution in an urban background area , 2000 .

[15]  P. Hari,et al.  Characterization of atmospheric trace gas and aerosol concentrations at forest sites in southern and northern Finland using back trajectories , 2000 .

[16]  Liisa Pirjola,et al.  Characteristics of the atmospheric particle formation events observed at a borel forest site in southern Finland , 2000 .

[17]  Ari Laaksonen,et al.  Analysis of the growth of nucleation mode particles observed in Boreal forest , 1998 .

[18]  L. Pirjola,et al.  Sulfate aerosol formation in the Arctic boundary layer , 1998 .

[19]  U. Baltensperger,et al.  The Jungfraujoch high‐alpine research station (3454 m) as a background clean continental site for the measurement of aerosol parameters , 1998 .

[20]  A. Stohl,et al.  The influence of Kola Peninsula, continental European and marine sources on the number concentrations and scattering coefficients of the atmospheric aerosol in Finnish Lapland , 1997 .

[21]  J. W. Fitzgerald,et al.  Marine boundary layer measurements of new particle formation and the effects nonprecipitating clouds have on aerosol size distribution , 1994 .

[22]  Trevor D. Davies,et al.  Cluster analysis: A technique for estimating the synoptic meteorological controls on air and precipitation chemistry—Results from Eskdalemuir, South Scotland , 1992 .

[23]  Trevor D. Davies,et al.  Cluster analysis: A technique for estimating the synoptic meteorological controls on air and precipitation chemistry—Method and applications , 1992 .

[24]  K. T. Whitby.  THE PHYSICAL CHARACTERISTICS OF SULFUR AEROSOLS , 1978 .

[25]  S. Twomey.  Pollution and the Planetary Albedo , 1974 .