11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Thursday, 6 June 2002
Microphysical observations of a cold frontal passage during ACE-Asia
Justin R. Peter, Monash University, Clayton, Vic., Australia; and S. T. Siems, J. B. Jensen, P. B. Krummel, and J. Hacker
During April/May 2001, the intensive field phase of the third Aerosol Characterisation Experiment (ACE-Asia) was undertaken as part of the International Atmospheric Chemistry (IGAC) Program. Jointly, the Japanese Science and Technology administration funded 'A Core Research Project for Evolutional Science and Technology Asian Atmospheric Particulate Environment Change Studies - Experiment 1' (APEX-E2). One of the primary aims was to characterise the mineral and anthropogenic aerosols advecting from the Asian continent with the ultimate aim of better understanding of their impact on climate. The Australian component of ACE-Asia/APEX-E2 was based in Kagoshima; utilising Airborne Research Australia's (ARA) Beechcraft King Air fitted with the standard suite of thermodynamic and dynamic measuring instruments. Also on board were aerosol and cloud droplet sizing instruments (ASASP,FSSP,2D-C and CAPS) and cloud condensation nuclei (CCN) counters (TSI 3010 and TSI 3025).

On 24 April 2001, an area of frontogenesis was identified southwest of Kagoshima. Two flights were flown to characterise aerosol evolution and processing through the frontal passage. Aircraft observations (microphysical, dynamical, thermodynamical and radiative) were made in the region preceding the cold frontal boundary and then later in the cold subsiding air following the front. Stacks were flown close to the ocean surface and high up in the outflow region of the front ( 500-7000 m). Initial results for the pre-frontal flight show a layer of clean air located at 850-650 hPa, between two 'dirty' layers , indicating a differing trajectory history for the clean air.

Some preliminary results of observed aerosol and cloud droplet spectra are presented. Averaged microphysical profiles are also presented and comparisons made between the pre-frontal and post-frontal regions.

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