General comments

Satheesan et al. introduced a CCD-modified algorithm for retrieving tropospheric ozone columns from TROPOMI measurements. This study also includes validation efforts using independent ozonesonde reference datasets and comparisons with operational TROPOMI CCD products. The main difference of their algorithm to the standard CCD algorithm is in estimating the stratospheric columns above the convective clouds and adjusting the ozone amount between cloud height and 270 hPa. This study experiments the use of a local reference sector to broaden the application range of the CCD based method from the tropical region (20S-20N) to mid-latitudes, compared to the standard CCD method that use a fixed (pacific) reference sector assuming zonal invariance of the stratospheric ozone in the tropics. The findings hold significant scientific value for the space-borne atmospheric monitoring community and align well with the scope of AMT. However, the authors are requested to address the following scientific comments and revise the manuscript for its acceptance.

Specific comments

C1 This manuscript needs a substantial revision to clearly convey the similarities and differences among the presented algorithms. The four algorithms involved in this work is 4.1 CPC algorithm, 4.2 CLC algorithm, 4.3 CLCT algorithm as well as the standard CCD algorithm (3.2). The algorithm descriptions span from pages 5 to 11, including an extensive repetition of common processes shared across each algorithm. Moreover, it is inappropriate to treat them as independent algorithms for CPC, CLC, and CLCT, respectively, they should be specific option details in the process of the reference sector choice (pacific or local) and the adjustment schemes (climatological, regression).    

C2 Revise the structures. My suggestion is

1. data

• TROPOMI (bring here 2.1 and introduce the TROPOMI total ozone/cloud/CCD TCO products)
• ozonesonde
• Algorithms

First describe the general common process. And then specify implementation details in each section.

• standard CCD
• Authors’ algorithm

4   results

C3 5.1 Uncertainty Budget. The error budget estimation method needs to be improved. According to Equation 1, the uncertainty estimate is almost dependent on the number of samplings for each grid box. But, In the local reference sector process, the longitudinal range of the reference sector is expanded until the minimum of sampling encounters, affecting the inhomogeneity of the samplings. The error term to the inhomogeneity of the samplings caused by stratospheric variability and upwelling of the boundary layer into the upper troposphere, should be included.

 C4. Section 5.2 should be significantly revised. It is not proper to deliver comparison results for each station. My suggestion is discussing the validation results, separately w.r.t 1) geophysical variables (e.g. total column ozone, cloud pressure, aerosol index) using all pairs from all stations (not each station) 2) seasonal comparison for maybe several sectors (e.g., pacific region, subtropical), 3) Figure 12 and Table 1 and a few stations from Figure 8 to summary the validation results.

C5. It is more interesting to see the comparison/evaluation results for ACCO with each meteorology against ozone sonde, rather than TCO.

Interesting ideas some more details might be added see detailed comments