Dear Alyson

As you can see, the two reviewers are generally positive about the scientific importance of your work and believe your manuscript is substantially improved. But they have remaining concerns - that I largely share - about how faithfully the methods used are able to separate cause and effects. Among the key points, they address the relationship of LWP to meteorology, in particular entrainment of dry air from aloft, and how well aerosol and clouds can be compared when using the MODIS AI column integrated index. I would also like to see greater discussion of the sensitivity of the MODIS AI and associated results to swelling since this correlates so strongly with RH.

For a guide of interactions between stability, RH and LWP it might be worth looking at the paper by de Roode et al. (2014): A mixed-layer model study of the stratocumulus response to changes in large-scale conditions

I will look forward to a revised manuscript.

Best regards,


Tim Garrett

Dear Alyson Douglas,

I am recommending your paper for it being forwarded for publication in ACP. Congratulations.

Aside from the important insights provided on the varying roles of aerosols in changing clouds globally, I see the work as providing important guidance to researchers on the issues that need to be considered to avoid obtaining "false positives" in aerosol indirect effect studies. I hope that further work can focus on better constraining the uncertainties now mentioned in your article of using an optically determined column integrated quantity for measuring aerosol concentration. Tracer Transport Modeling has its own problems but can be used to co-locate pollution plumes with clouds horizontally and vertically without concerns about swelling in humid environments.

Regards

Tim Garrett