Table 3. Indirect Effects on Marine Stratocumulus

	In Situ Aircraft Observations	LES or ERMa Simulations
Twomey effect
CDNC increases due to Na increase	Ferek et al. [1998]; Taylor et al. [2000] of MAST; Brenguier et al. [2000] of ACE2; Feingold et al. [2006]; this study	Feingold et al. [1994]; Kogan et al. [1996; 1997]; Jiang et al. [2001; 2002]; Ackerman et al. [2004]; Lu and Seinfeld [2005]; this study
Smaller droplet size due to CDNC increases	Hudson and Yum [1997] of FIRE and ASTEX; Taylor et al. [2000] of MAST; Brenguier et al. [2000] of ACE2; Feingold et al. [2006]; this study	Feingold et al. [1994]; Kogan et al. [1996; 1997]; Jiang et al. [2001; 2002]; Lu and Seinfeld [2005]; this study
Second Indirect Effect
Drizzle suppression due to higher CDNC (Albrecht effect)		
Fewer drizzle drops	Ferek et al. [1998]; Ferek et al. [2000] of MAST; this study	This study
Smaller drizzle rate	Ferek et al. [2000] of MAST; this study	Jiang et al. [2001; 2002]; Ackerman et al. [2004]; Lu and Seinfeld [2005]; this study
Column LWP or local LWC responses due to drizzle suppression		
LWP/LWC increase	Taylor et al. [2000] of MASTb; this study of the ship track impacted cloud	Jiang et al. [2001, 2002]; Ackerman et al. [2004] for ASTEX, FIRE (CDNC <225 cm-3)c and DYCOMS-II (CDNC <35 cm-3)c; Lu and Seinfeld [2005] for ASTEX; this study of the ship track impacted cloud
LWP/LWC decrease	Ferek et al. [2000] of MAST; this study of the overall 13 clouds sampled	Feingold et al. [1997]; Ackerman et al. [2004] for FIRE (CDNC >225 cm-3)c and DYCOMS-II (CDNC >35 cm-3)c; Lu and Seinfeld [2005] for FIRE
Entrainment rate increases	None	Ackerman et al. [2004]; Lu and Seinfeld [2005]
Cloud cover increases due to drizzle suppression	Noned	Ackerman et al. [2003]
Lifetime increases due to drizzle suppression	None	None
Dispersion effect
Narrower droplet spectral width due to higher CDNC or Na	Hudson and Yum [1997] of FIRE and ASTEX; Miles et al. [2000]e; in-flight data for all clouds and flight-averaged data for clouds with CDNC >100 cm-3 in Pawlowska et al. [2006]; this study of the ship track impacted cloud	Feingold et al. [1997]; Lu and Seinfeld [2006]; this study
Decrease or increase of relative dispersion due to higher CDNC or Na		
Relative dispersion decrease	Miles et al. [2000]e; in-flight data for all clouds in Pawlowska et al. [2006]; this study of the ship track impacted cloud	Feingold et al. [1997]; Lu and Seinfeld [2006]; this study
Relative dispersion increase	Liu and Daum [2002]; Flight-averaged clouds in Pawlowska et al. [2006]; this study of the overall 13 clouds sampled (on the basis of Na)	None

aEddy resolving model is a 2D version LES.
bDrizzle occurrence was inferred by satellite, and LWP is from microwave radiometer.
cOr the threshold of surface drizzle rate of 0.1 mm day-1.
dThis effect is difficult to measure by aircraft and is mostly seen in satellite studies, e.g., Kaufman et al. [2005] and Rosenfeld et al. [2006].
eCompiled database of "marine" and "continental" low clouds. We assume that "continental" clouds are more polluted than marine clouds.