AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Scanning Flow Isothermal CCN Analysis (SFICA): A New Method for Measuring CCN
MARY KACARAB, Tomi Raatikainen, Greg Kok, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 202 Working Group: Instrumentation and Methods
Abstract The ability of atmospheric aerosols to act as cloud condensation nuclei (CCN) plays a complex and important role in aerosol-cloud interactions and their effect on the global climate (IPCC 2014). Currently, CCN activity is most often evaluated using a continuous-flow streamwise thermal gradient CCN counter (CFSTGC) in either a constant flow regime utilizing different temperature gradients along the column to generate different supersaturation conditions or a constant temperature gradient utilizing scanning flow CCN analysis (SFCA) methods to achieve a higher time resolution through ranges of supersaturations. This work presents a novel method to generate supersaturation environments within the column without the need for a temperature gradient, solely through manipulation of the pressure drop across the instrument column. This method is first demonstrated and evaluated on the full-size commercial CFSTGC instrument both in the laboratory and in the field during the 2016 NASA ORACLES campaign. The zero temperature gradient method is further applied to a lightweight, miniaturized isothermal instrument. The decreased size and isothermal column allows for a substantial reduction in the cost of the instrument and furthermore opens up possibilities for measuring CCN on unmanned aerial vehicles (UAVs). This work opens up a significant opportunity for establishing a network of low-cost and highly accurate CCN measurements, which are critical for an increased understanding of the radiative and hydrological impacts of regional aerosols on clouds.