Scattering coefficient, size distribution and the transport process of tropospheric aerosol in the Arctic region observed with an aircraft during ASTAR 2000/2004 and AAMP 2002 campaign in spring

Abstract

Airborne aerosol measurements of the Arctic haze were carried out during three campaigns, Arctic Study of Tropospheric Aerosol and Radiation 2000 (ASTAR 2000), the Arctic Airborne Measurement Program 2002 (AAMP 2002) and ASTAR 2004. Aircraft used for the campaigns were Dornier for ASTAR 2000 2004 and Gulfstream II for AAMP 2002. For all measurements aerosol particles were introduced into the cabin through stainless inlets and distributed to several instruments via a diffuser. Scattering coefficient of aerosol particles measured with an integrating nephelometer during the Arctic haze period showed a distinct difference between the lower, i.e. up to around 4000 m, and higher troposphere. Meanwhile, scattering coefficients in higher troposphere during the Arctic haze were in the same degree with those after the Arctic haze. Size distribution obtained from the data of a particle counter indicates that aerosol particles in accumulation mode during the Arctic haze have larger geometric mean diameter than those after the haze season, which reflects the aged air mass in the Arctic haze. "Curtain flight" which was carried out to reveal the fine structure of the haze layer showed that aerosol particles are transported in the isentropic plane.