AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Particle Nucleation and Vertical Profiles of 8-15 nm Particles at the DOE Southern Great Plains Facility from 300m to 1000m Above Sea Level
JOHN ORTEGA, James N. Smith, James Greenberg, National Center for Atmospheric Research
Abstract Number: 520 Working Group: Advances in the Physics and Chemistry of New Particle Formation and Growth
Abstract New particle formation events have been witnessed globally in widely varying environments. It is generally assumed that particle formation events require a low background aerosol population so that condensable oxidized organic gases and sulfuric acid clusters will form stable clusters rather than condense onto existing particles. There have been numerous campaigns and long-term monitoring stations based on ground-level measurements that have observed the formation of nucleation-mode particles. However, simultaneous measurements that show the horizontal and vertical extent of these new particles and associated concentration of condensable gas-phase species is difficult. The technology for remote sensing (satellite-based) techniques is not available. Measurements of new particle formation from airplanes is not practical because of expense, the unpredictable nature of the events, and the limited amount of time and space over which sampling can occur. During the 2013 Southern Great Plains-New Particle Formation Study in Oklahoma, vertical profiles (from 0 – 1000 m above ground level) of aerosol number concentration were made using two condensation particle counters (CPC) on a tethered balloon. The CPCs were configured to detect particles with diameters larger than 8 and 15 nm respectively. The particle concentration profiles between these two diameters were then calculated by taking the difference of the two measurements. A small meteorological package was used to obtain pressure (altitude), temperature, wind speed and wind direction. On several occasions, small particle concentrations were dramatically higher between 300 and 500 m above the ground than at the surface, indicating that nucleation occurred aloft. On other occasions, particle concentrations were generally homogeneous. Concentrations above the mixed layer (~600-800 m above ground) were generally much lower. This presentation will summarize the vertical measurements, instrument performance, meteorological conditions, and comparisons with concurrent ground-based particle size distributions (both at the launch site and 100km to the south).