The article titled “Divergent Drivers of Aerosol Acidity: Evidence for Shifting Regulatory Regimes in a Coastal Region” combines field observations, multiphase buffer theory, and ISORROPIA simulations to investigate aerosol pH dynamics in Shenzhen under typhoon and non-typhoon conditions. The work holds scientific value and practical relevance. Some issues need to be addressed.

1. The Introduction could be more concise and refined. I recommend condensing the literature review and stating the novelty and contributions of this study more explicitly. While the first two paragraphs serve as informative background, it is also advisable to supplement with additional research reviews focusing on aerosol acidity in coastal cities.
2. Is the composition of atmospheric aerosols, as well as temperature and humidity, still affected by the typhoon for a period immediately after the typhoon ends? How can such residual effects be distinguished from or eliminated when analyzing non-typhoon events?
3. Lines 224-228, I didn’t find the detailed calculation instructions on how to determine the peak buffer pH value shown in Figure 2. Is the curve shown in Figure 2 calculated based on the average of all typhoon and non-typhoon scenarios? More clarity is needed for the relevant description.
4. Line 240, the method to quantify the changes in aerosol pH (ΔpH) between typhoon and non-typhoon scenarios attributable to individual drivers should be presented in detail in the main text. How to obtain the result shown in Figure 3?
5. Lines 288-290, I am unclear about what the pH values being compared in Figure 4 actually mean. The description here is a bit confusing and not clear enough.
6. The unit formats used in the manuscript are inconsistent and should be standardized.

The authors conducted observations at the coastal Xichong site in Shenzhen, integrated field data, multiphase buffer theory, and ISORROPIA simulations to comparatively analyze the buffering capacity and driving factors of aerosol pH during typhoon and non-typhoon periods. They found that during non-typhoon periods, aerosol pH is buffered by the NH4+/NH3 pair with relative humidity as the main driver, while during typhoon periods, it is dominated by sea salt-derive NVCs.

This study points out the limitations of the multiphase buffer theory in scenarios dominated by NVCs, which is innovative. The overall quality of the study is relatively high, and after addressing the following comments, I believe it meets the quality requirements of Atmospheric Chemistry and Physics.

The detailed comments are as follows.

1. What does “constent aerosol water” in the Abstract mean? Why is this parameter considered?

2. The Introduction lacks a review of how the multiphase buffer theory explains the driving factors of pH.

3. This study uses ISORROPIA to calculate the acidity of inorganic aerosols, and it is necessary to define the boundaries at an appropriate position.

4. Figure 1: It is suggested to use arrows to indicate wind direction instead of degrees.

5. Figure 2: Based on the calculations using the multiphase buffer theory, can it be indicated that the buffer peak is the range where the pH value should lie? Is there evidence from other studies to support this, or is it a coincidental result of this paper?

6. Do Figure 2 and Figure 3 contradict each other? The former indicates that the buffer capacity during non-typhoon periods is stronger, so why is the ΔpH here much larger than that during typhoon periods? This is especially considering that the difference in the standard deviation of the data reported in Figure 1 is not significant.

7. Figure 4: What previous evidence led the authors to want to fix AWC? And to what value is AWC fixed? The mean? The median?