Abstract
Abstract. This paper analyses aerosol particle number size distributions, particulate absorption at 570 nm wavelength and carbon monoxide (CO) measured between September 2006 and January 2010 at heights of 50 and 300 m at the Zotino Tall Tower Facility (ZOTTO) in Siberia (60.8° N; 89.35° E). Average number, surface and volume concentrations are broadly comparable to former studies covering shorter observation periods. Fits of multiple lognormal distributions yielded three maxima in probability distribution of geometric mean diameters in the Aitken and accumulation size range and a possible secondary maximum in the nucleation size range below 25 nm. The seasonal cycle of particulate absorption shows maximum concentrations in high winter (December) and minimum concentrations in mid-summer (July). The 90th percentile, however, indicates a secondary maximum in July/August that is likely related to forest fires. The strongly combustion derived CO shows a single winter maximum and a late summer minimum, albeit with a considerably smaller seasonal swing than the particle data due to its longer atmospheric lifetime. Total volume and even more so total number show a more complex seasonal variation with maxima in winter, spring, and summer. A cluster analysis of back trajectories and vertical profiles of the pseudo-potential temperature yielded ten clusters with three levels of particle number concentration: Low concentrations in Arctic air masses (400–500 cm−3), mid-level concentrations for zonally advected air masses from westerly directions between 55° and 65° N (600–800 cm−3), and high concentrations for air masses advected from the belt of industrial and population centers in Siberia and Kazakhstan (1200 cm−3). The observational data is representative for large parts of the troposphere over Siberia and might be particularly useful for the validation of global aerosol transport models.
Highlights
The Siberian landmass hosts an ecosystem that is globally relevant for the atmospheric budget of carbonaceous greenhouse gases, such as CO2 and CH4 (Schulze et al, 1999; Lloyd et al, 2002), and aerosol particles
Fits of multiple lognormal distributions yielded three maxima in probability distribution of geometric mean diameters in the Aitken and accumulation size range and a possible secondary maximum in the nucleation size range below 25 nm
For all integral parameters and all seasons the concentrations are higher at 50 m than at 300 m, with their ratio being highest in the number and lowest in the volume concentrations
Summary
The Siberian landmass hosts an ecosystem that is globally relevant for the atmospheric budget of carbonaceous greenhouse gases, such as CO2 and CH4 (Schulze et al, 1999; Lloyd et al, 2002), and aerosol particles. The secondary aerosol over boreal forests is predicted to exert a net cooling effect on global climate (Spracklen et al, 2008). In contrast to its global relevance, Siberia is still poorly represented in atmospheric observation systems. Many previous atmospheric aerosol studies for Siberia have relied on satellite data (e.g., Cahoon et al, 1994; Stocks et al, 1998). In-situ physical, chemical and optical properties of aerosol particles have only been scarcely available
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