This study presents the analysis quantifying the relationship among PM2.5 concentration, visibility and planetary boundary layer (PBL) height for tow haze events i.e. one long–lasting haze and one fog–haze mixed event in Beijing. Authors found negative relationships between visibility and PM2.5 and between PM2.5 and PBL height and suggested possible feedbacks among PM2.5, PBL, and/or humidity whereas the PBL plays a dominant roles. Authors also found a double inversion layer formed in both typical events, which played critical roles in maintaining and enhancing the long–lasting polluted events. The topic of this paper is interesting and is suitable for ACP. However, major revisions are required before I can accept this manuscript for publication. Authors did a lot of analysis on the relationships among PM2.5, visibility and PBL height. However, the findings are not new and these relationships were already reported in many previous studies. What’s really new probably is the influence of double inversion layer on the meteorology and PM2.5, which deserves more in-depth analysis and discussion. In addition, the current analysis mainly focus on the correlations and co-changes of PM2.5, PBL Height and visibility, more substantial analysis and discussion of the physical explanation are required for those relationships, for examples, courses and effects of those quantities as well as the role of PBL height in it.

Authors have addressed all comments and paper can be accepted for publication as it is.