This paper evaluates the performance of five atmospheric reanalyses (ERA5, JRA-3Q, MERRA-2, M2-SCREAM, and CAMS) in representing the climatological distributions of trace gases (water vapor, ozone, and carbon monoxide) in the upper troposphere and lower stratosphere (UTLS) above the Asian summer monsoon (ASM). The study uses data from the Aura Microwave Limb Sounder (MLS) satellite observations to assess how well these reanalyses capture the seasonal and regional variations of trace gases. The paper also investigates the roles of advection, physical processes, and data assimilation in shaping these distributions.. The manuscript can be accepted for publication, however I have few comments which are mentioned below 

(1)  To look into the seasonal evolution of tracers in the UTLS from prior to monsoon to post monsoon you have considered the period from May to October. However, majority of the studies mainly focussed on the chemical composition within ASMA between July and August corresponding to peak monsoon months (or June to September). Why did you consider the zonal anomalies of the PCW, PCO3 and PCCO from May to October.

(2)  There is a shift in the bias (both for O3 and WV) in all the reanalysis compared to MLS which has limitations due to the coarser vertical resolution.  Is the vertical resolution in all the reanalysis used in this study are nearly same?

(3)  For better clarity in the interest of readers, it would be useful if you mention in the figure caption what the values in the square brackets represent, though you have mentioned in the body of the manuscript.

(4)  What could be the possible reasons for the negative and positive tendencies in the water vapor over the southern and northern part of the Tibetan Plateau?  Which dominate (physics, advection, assimilation)?

Lastly, I would suggest to write many simpler sentences when much information has to be conveyed so that it would be easy for the readers. 

Thank you