Meteorological events and transport patterns in ACE-Asia

The Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) intensive phase took place from 30 March to 4 May 2001, involving extensive aerosol observations from aircraft, ship, and ground stations. Meteorological events of significance to the ACE-Asia intensive observations made during this period were identified and analyzed using a combination of gridded meteorological analysis fields, observations, and analyses of precipitation, atmospheric radiation distributions, and other variables, and products prepared from these data. The observed flow characteristics were found to be close to the center of the range of interannual variation, with most anomalies spatially confined and small in magnitude. The occurrence and distribution of midlatitude cyclones which had an impact on the circulation and transport patterns affecting the area of the campaign were close to the climatological mean. Total aerosol scattering and the fraction caused by submicron particles, and trajectory analysis results from points along the flight track of the C-130, were used to examine the relationship between the aerosol distributions and transport patterns and the meteorological situation. Notably strong coarse-mode scattering was observed at low altitudes in post cold-frontal circulations during dust outbreaks, and very strong mixed-mode scattering occurred in plumes from polluted areas flowing offshore removed from important surface or upper air features.