Initial Characterization Of Splash Artifacts From Two Airborne Aerosol Inlets During VOCALS Campaign

LUCAS CRAIG (1), Allen Schanot (2), Arash Moharreri (1), Suresh Dhaniyala (1), Dave Rogers (2), Antony Clarke (3)

(1) Clarkson University, Potsdam, NY, (2) NCAR/RAF, Broomfield, CO, (3) University of Hawaii, Honolulu, HI

     Abstract Number: 179
     Last modified: April 28, 2010

Abstract
There is a need for aerosol inlets that can accurately sample from airborne platforms under a range of atmospheric conditions. Of particular importance is the need to accurately sample aerosols inside cloud systems. Aircraft-based aerosol sampling in clouds is complicated by the breakup of the activated liquid droplets on collision with the inlet walls and the creation of a large number of artifact particles (or splatter particles) of the same size as the non-activated or interstitial particles. Because of this complication, measurements of CN inside of clouds are often just discarded. In this study, we examine the extent of the splatter artifact problem and its dependence on cloud droplet properties (size and number) using data from a recent aircraft-based field campaign (VOCALS). The response of two different inlets – NCAR’s forward facing cone (FFC) and a traditional solid diffuser inlet (SDI) – over a range of cloud systems is studied. In warm marine-stratus clouds, the CN measurements with the FFC inlet are seen to be largely consistent with expectations of conservation of total particle number concentration inside (activated droplets + interstitial particles) and outside clouds (background aerosol). With the SDI inlet, the CN measurements are enhanced significantly inside cloud systems because of the generation of splash artifact particles. This paper presents the details of the CN measurements in cloud systems obtained with these two inlets as a function of cloud properties. We will also describe the reasons for the differences in the inlet measurements based on our computational fluid dynamics (CFD) study.