Thank you for providing your revised manuscript and your response to referee comments. The revised manuscript is improved and some of the referee comments have been adequately addressed. However some referee comments, particularly regarding details on the methods and relation of this analysis to previous work on trends, need further work.

Before the manuscript can be accepted for publication, the authors are requested to make the following modifications to address referee and editorial comments. There are also numerous grammatical errors throughout the manuscript. Careful editing of the manuscript is required.

Abstract
Please state the time period analysed by the study. This is important, given the rapid changes in emissions and pollutants in China.

This last statement in the abstract maybe needs some thought: ”and particularly the reduction of nitrate, sulfate and their precursor gases would contribute towards better air quality in China”. Reduction in these components would improve visibility due to aerosol water uptake as you have demonstrated, but is this the same as improving air quality? This statement also needs to include the caveat that SO2 and NOx emissions have already declined substantially since the period studied in this paper.

Introduction

A concise review of previous work on trends in air pollution over China in recent years would be helpful. This was suggested by Referee #2, but not fully addressed in the revised manuscript. A paper that I co-authored (Silver et al., 2018) includes relevant references that could be cited here:
https://iopscience.iop.org/article/10.1088/1748-9326/aae718/meta

Methodology

More additional details on the methods are needed to help the reader understand the paper. This was suggested by Referee #2 and not fully addressed in the revised manuscript. Specifically:
1) Time periods of the different datasets, particularly the visibility dataset.
2) Please provide brief details on the model product that you use. You use a model-satellite derived product and this needs to be stated.
3) More details on the AMS data. In particular, time period and location.
4) Details on the SCIAMACHY product including a reference.

Section 3.1 There is an indication in Figure 2 that the long-term trend reversed in around 2007 to 2008, approximately the same time previous studies have reported a peak in SO2 and NOx emissions in China. Given the previous literature on this point I think this requires some brief discussion. See the related comment from Referee #2 on this point.

Section 3.2 See Referee #2 comment on trends. There have been a number of papers written on NO2, SO2, and PM2.5 trends over China that are not referred to in the revised manuscript. It is not clear how the revised manuscript either confirms or contradicts previous analysis. Please clarify. Some important papers that report recent trends in SO2 and NO2 over China include:

Krotkov N A et al 2016 Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015 Atmos. Chem. Phys. 16 4605–29
Ling Z, Huang T, Zhao Y, Li J, Zhang X, Wang J, Lian L, Mao X, Gao H and Ma J 2017 OMI-measured increasing SO2 emissions due to energy industry expansion and relocation in northwestern China Atmos. Chem. Phys. 17 9115–31
Van Der A R J, Mijling B, Ding J, Elissavet Koukouli M, Liu F, Li Q, Mao H and Theys N 2017 Cleaning up the air: effectiveness of air quality policy for SO2 and NOx emissions in China Atmos. Chem. Phys. 17 1775–89
Irie H, Muto T, Itahashi S, Kurokawa J and Uno I 2016 Turnaround of tropospheric nitrogen dioxide pollution trends in China, Japan, and South Korea Sola 12170–4
PM2.5 concentrations have also declined recently across China as demonstrated by surface observations (Silver et al., 2018) and satellite studies.

Does the increase in NO2 and SO2 after 2007 contradict previous analysis. This requires some comment.

Section 4. It is important to note that the present study ends in 2010 (2012?). There have been large reductions in Chinese NOx and SO2 emissions since 2012. This is a crucial caveat that needs to be mentioned in the conclusions.

Figure 5. Add an explanation of the x-axis to the figure caption.