This manuscript investigates water vapor isotopes (H2O and HDO) over West Africa, focusing on the West African Monsoon (WAM). Using satellite data from IASI, AIRS, and TROPOMI, the study analyzes moisture pathways and isotopic variations during different monsoon phases. Key findings include an anti-correlation between H2O and δD over the Sahel during monsoon convection, driven by dry air intrusions, while the Guinea Coast shows moist, enriched air without significant δD depletion. The study highlights the value of paired isotopic observations in understanding tropical convection and moisture processes in the region. Overall, this manuscript is well written, and no additional observations or model simulations seem necessary. However, a few minor revisions or updates could help clarify the study and improve the understanding of WAM mechanisms.

 

1. Monsoon retreat phase

The monsoon consists of rainfall systems moving the convection area north and south. However, this study covers the monsoon onset but lacks analysis of the retreat (withdrawal) phase. There could be asymmetry due to land-sea contrasts and seasonal mean state differences.

 

2. Figures showing contrast

Throughout the figures (e.g., regarding non-rain & post-rain periods, Guinea Coast & Sahel), the differences are not clearly visible (except during the monsoon peak month of August) for readers to capture the changes in H2O and δD pairs. The authors may consider adding additional figures highlighting these differences to better illustrate which processes or regions are associated with enrichment or depletion as moisture changes.

 

3. Satellite dataset uncertainty

The authors mention the previously reported uncertainty in the three satellite datasets, but the reliability of using them specifically for the WAM region is not clearly addressed. Please quantify this uncertainty more explicitly, not only through percentage contours or whisker plots for individual datasets but also by considering the spread between the two datasets (IASI and AIRS). Additionally, the authors could emphasize the benefits of using water isotopes, for instance, by showing more distinct anomalies in δD compared to H2O in those datasets.