This manuscript presents the development and validation of a new ozone dataset, generated by applying a Complete Data Fusion (CDF) algorithm to combine limb observations from MIPAS with nadir observations from IASI for the 2008–2011 period. Overall, the authors have done good job in detailing the methodology, including the tuning process across nine different configurations. This systematic approach highlights the trade-offs in terms of bias, degrees of freedom (DOFs), and retrieval errors. The validation against ozone sonde data spans multiple years and latitudinal bands, and the scientific motivation is clear: the need for high-resolution data in the Upper Troposphere–Lower Stratosphere (UTLS) to better understand processes such as stratospheric intrusions, particularly in complex regions like the Himalayas.

To some extent, the authors clearly demonstrate the improvements of the fused product relative to ozone sonde measurement. Their key finding is that  that the new dataset offers higher DOFs and reduced uncertainty compared to individual MIPAS and IASI retrievals, especially in the UTLS region. The manuscript  illustrates that stratospheric ozone profile information from MIPAS helps constrain the ozone profile at lower altitudes. Moreover, the authors carefully analyse the altitude- and latitude-dependent biases IASI data and apply a bias correction that significantly enhances the quality of the final product, making it more suitable for scientific applications.

While the manuscript is relatively well rounded, a few suggestions could further enhance its impact. First, the dataset covers a relatively short period (2008–2011), which may limit its utility for chemical modelers for the chemistry/dynamics related evaluations. To better showcase the new data sets unique value, I strongly recommend including a specific case study—such as a well-documented stratospheric intrusion event—where the fused product demonstrates improved agreement with ozone sonde data compared to reanalyses like CAMS or ERA5. Additionally, given the manuscript’s focus on Stratosphere-Troposphere Exchange (STE) in the Himalayan region, it is noteworthy that the ozone sonde stations shown in Figure 1 are predominantly located in Europe and the United States. Incorporating independent ozone sonde data from the Himalayan region would allow for a more targeted evaluation of the fused dataset in its primary area of interest. Finally, I strongly encourage the authors to adopt an open-data policy. Making the dataset publicly available would facilitate broader evaluation and application by the research community, thereby maximizing the impact of this important work. The current statement that data is available upon request may limit its accessibility and utility.