Long term particle size distribution measurements at Mount Waliguan, a high-altitude site in inland China

Abstract

Abstract. Particle number size distributions in size range 12-570 nm were measured continuously at Mount Waliguan, a remote mountain-top station in inland China. The station is located at the altitude of 3816 m a.s.l., and some 600-1200 m above the surrounding area. The measurement period lasted from September 2005 to May 2007. The measurements were verified with independent CPC measurements at the same site. The average particle concentration in ambient conditions was 2030 cm −3 , which is higher than the values measured at similar altitude in other regions of the world. On average, the Aitken mode contributed to roughly half of the particle number concentration. The concentrations were found to be higher during the summer than during the winter. The diurnal variation was also investigated and a clear pattern was found for the nucleation mode during all seasons, so that the nucleation mode particle concentration increased in the afternoon. The same pattern was visible in the Aitken mode during the summer, whereas the accumulation mode did not show any level of diurnal pattern during any season. Excluding the nucleation mode, the average day-time particle concentrations were not significantly higher than those measured at night-time, indicating no systematic pattern of change between planetary boundary layer conditions and free troposphere conditions. In air masses coming from east, the number concentration of particles was higher than in other air masses, which indicates that the air Correspondence to: N. Kivekäs (niku.kivekas@fmi.fi) mass might be affected anthropogenic pollution east of the station. Also other factors, such as active new-particle formation, keep aerosol number concentrations high in the area.

Classifying aerosol type using in situ surface spectral aerosol optical properties

“…Lower SAE values mean the aerosols from this trajectory cluster are larger, and AAE values near and above 1.5 likely mean a dust and/or carbonaceous aerosol mixture (Cazorla et al, 2013). These results support those of Che et al (2011) and Kivekäs et al (2009), which cite deserts as aerosol sources from western wind sectors at WLG. clusters 1 and 2 are most similar in terms of median SAE and AAE values, though the map shows that Cluster 1 trajectories traveled farther in the 3-day period, and thus had faster wind speeds.…”

“…Though maritime airflow is predominant, some anthropogenic influences from other airflows is observed (Oltmans et al, 2008 High-altitude station located on the dry, arid Tibetan Plateau in China. The site experiences clean or dusty air masses coming in from the west and anthropogenically influenced and polluted air masses coming from the east (Kivekäs et al, 2009;Che et al, 2011). Sites are categorized based on the site's geography and surrounding land use.…”

Aerosol optical properties and radiative forcing in the high Himalaya based on measurements at the Nepal Climate Observatory-Pyramid site (5079 m a.s.l.)

“…This study showed elevated concentrations of PM 2.5 especially during the February-May season (59±61 µg/m 3 ) paralleled with substantial extinction (aerosol optical depth δ500 nm=0.37±0.25) with a dominance of both organic and elemental carbon from combustions sources as well as elements associated with dust emission. Additional measurements recently reported by Komppula et al, 2009, Hyvarinen et al, 2009, Kivekäs et al, 2009 for research stations located in India (Mukteshwar, 2180 m) and China (Mt. Waliguan, 3816 m) confirmed presence of elevated concentration of particles lifted up to high altitude by both local wind dynamics and regional/long range transport.…”

A statistical analysis of North East Atlantic (submicron) aerosol size distributions

“…Additionally, Charron et al (2007) presented an examination of the source signature or origin signature represented by particle number size distribution and modal diameters measured at a rural receptor size in southern England while Beddows et al (2009) was able to reduce the complexity of the different rural, urban, and curbside atmospheric particle size data according to the temporal and spatial trends of the clusters. Whilst a number of intensive field studies have been focusing on average monthly datasets, clustering analysis on year long particle size distributions measurements are scarce (Engler et al, 2007;Kivekäs et al, 2009;Venzac et al, 2009). …”