Optical thickness of two different layers, measured during one of the research flights	Comparison of size distributions derived from measured optical thickness and measured directly

Aerosols (small atmospheric particles) streaming off the East Asian continent have been observed to travel as far as the US. Chemically and physically they are one of the most heterogeneous aerosol populations on Earth, with contributions from Gobi desert dust, Chinese industrial and domestic pollution, and oceanic compounds. In an effort to better understand this cocktail, the international aerosol community recently undertook an intensive field campaign, centred off the coast of China, South Korea and Japan. Three ships and four aeroplanes, packed with scientists and their equipment, patrolled the area, while other scientists set up ground stations, and satellites orbited overhead. The idea was to measure everything that could be measured, in order to test the internal consistency of equipment, measurement strategies, and models.

The UNSW Atmospheric Physics group has been working with a team from NASA’s Ames Research Center to analyse sunphotometer data taken from instruments flown on two of the planes. These instruments measure attenuated sunlight for a number of different wavelengths. From these data we have been able to deduce the size distribution of the aerosol particles, and often observe quite different properties in different layers — Gobi desert dust particles are generally larger than industrial pollution, for example. These results are in good agreement with results from Caltech’s aerosol samplers flown on the same planes, confirming our analysis.

Maja Kuzmanoski, Gail Box and Michael Box