It may sound seem like a small quibble to you, but as someone who's spent time studying CCN, it makes me very uncomfortable when you refer to the variable “CCN concentration”. Without a stated supersaturation, it's not a properly defined quantity. I know that you do eventually specify that the observations are at 0.2%, and you imply (though never clearly state, I believe) that the modeled values are at the same supersaturation. In some cases you are referring to “CCN concentration” in a generic sense, and I'm OK with such usage. But when you are referring to the model variable or observed quantity, I'd ask that you use a well-defined variable. I'll suggest CCN_0.2 (so “0.2” as a subscript), similar to PM_2.5 but you can choose whatever format you like.

A tiny edit: p. 4, line 2: there's a missing space after “2013)”.