AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Comparison of Surface and Aircraft Cloud Condensation Nuclei Measurements in North Dakota
NICOLE BART, David Delene, University of North Dakota
Abstract Number: 501 Working Group: Aerosols, Clouds, and Climate
Abstract Particular matter suspend in the atmosphere that provides a surface for water vapor to condense onto is termed Cloud Condensation Nuclei (CCN). CCN activation produces cloud droplets that can eventually develop in to rain. Atmospheric CCN number concentration is determined using a counter that pulls an air sample into a supersatured environment and counts the number of droplets that form. CCN counters can be operated at the surface or deployed on aircraft to obtain measurements below cloud base. When conducting scientific analysis, cloud base is typically the most desirable location; however, the expense and difficulty of aircraft CCN measurements limits their availability. The research objective is to determine under what meteorological conditions surface based CCN measurements would be used to infer cloud base CCN concentrations. Knowing how accurately cloud base CCN concentrations can be inferred from surface measurements could allow long term, continuous surface-based measurements to be use in many aerosol-cloud interaction studies.
During the summer of 2010, seven aircraft flights were conducted in North Dakota that measured cloud based CCN concentrations. Concurrent with the aircraft measurement, surface CCN measurements were conducted in Grand Fork, North Dakota. Analysis of the cloud base and surface CCN concentrations shows a good correlation (R2=0.42); however, the surface CCN concentration was more than 50% lower than the cloud base CCN concentration. Both aircraft and surface CCN counters were calibrated using the same Scanning Mobility Particle Sizer (SMPS) system and show good agreement when running the CCN counts side by side. During the summer of 2012, additional aircraft and surface CCN measurements are planned.