PACDEX

The long range transport of dust and anthropogenic aerosols (e.g, black carbon, organics and sulfates), and air pollution from Eurasia, across the Pacific Ocean, into North America is one of the most wide spread and major pollution events on the planet. This plume passes through the Pacific Ocean extra tropical cloud systems, which are important climate regulators through their large radiative cooling effect. The effect of this mixed dust-pollution plume on the Pacific cloud systems and the associated radiative forcing is an outstanding problem for understanding climate change and has not been explored. The primary reason is the lack of an airborne platform that can sample the evolution of this plume in situ all the way across the Pacific Ocean.

The NSF/NCAR Gulfstream-V research aircraft (G-V) fills this observational gap and opens new doors for observing this great natural/man made phenomenon. PACDEX plans for a pilot study using Lagrangian sampling of this Eurasian-Pacific-North American dust plume. We will observe the evolution of the aerosol physical and chemical characteristics from the lower to the upper troposphere, the vertical and horizontal gradients in the CCN and ice nuclei across the Pacific, and cloud size spectra and liquid and ice water content. This pilot experiment is designed to exploit and demonstrate the unique capabilities of the G-V. The PACific Dust EXperiment (PACDEX) has the potential to open new frontiers of science by observing human impacts on the mixed-phase and ice-phase cirrus cloud systems.