You and your coauthors have addressed most of the referees' comments satisfactorily. However, I remain concerned about your boundary layer depth estimates based solely on MAX-DOAS data. Your analysis would be strengthened by independent BL depth estimates based on, e.g., radiosonde data from locations not too distant from Hefei. I believe that there are data available from Nanjing and Shanghai covering your observation period. Although there are only 2 observations per day, they are at times (at 0 and 12 UTC) that could yield some information about diurnal variability. This manuscript on BL depth climatology in China that is also currently in review might be worth looking at as well: http://www.atmos-chem-phys-discuss.net/acp-2016-564/

One other (and relatively minor) point on content: It would be helpful to add p values for the correlations summarized in Table 3.