## 4 Conclusions  
In this paper, we evaluated NUCAPS satellite sounding retrievals of temperature and water vapor for monitoring tropical cyclones while taking into consideration operational needs. To do this, a team of NUCAPS developers and tropical cyclone researchers collaborated to deploy dropsondes from aircraft for tropical cyclone cases that were relevant to operations and where satellite soundings could be useful for monitoring. Using the coincident temperature and water vapor profiles from five flights, we found that the NUCAPS vertical resolution of \(\approx\)2 km in the tropical North Atlantic was sufficient for resolving the atmospheric structure of the tropical cyclone environment, including dry and moist conditions. NUCAPS can be used alongside other satellite imagery or model data since the retrievals are independent of both. Presently, the NWS currently only receives the IR + MW retrieval. However, we found that the MW-only temperature retrieval has a relatively low RMSE (\(\approx\)1.33-1.62 K) above 600 mb when compared to scenes where a successful IR + MW retrieval is possible (\(\approx\)0.83-1.21 K). The MW-only water vapor retrieval performed well through the entire column, with RMSE values 23% near the surface compared with the 26% when a successful IR + MW retrieval was possible. Utilizing successful MW-only retrievals can help increase the yield of profiles when the IR + MW retrievals are rejected, such as near the tropical cyclone edge, where there is significant cloud coverage but no precipitation.  
More than a validation study, we viewed these flights as an opportunity to engage with end users, demonstrate how well NUCAPS can be provided in real time, and test new display tools. Although highly complex, NUCAPS was designed to be a fast, operational system, so we were able to perform collocations as soon as 20 min after the dropsonde release. Rapid processing was also possible because input MW and IR data were obtained immediately following the NOAA-20 and Suomi NPP overpasses from the Miami, Florida and Puerto Rico direct broadcast receivers. We also delivered gridded NUCAPS fields and diagnostics in real time during the flight using web-based tools. Hence, this study is also an operational evaluation, where we consider both the quantitative skill of NUCAPS and the operational feasibility. We encourage other satellite product developers to use this research to operations framework as they refine their operational products.  
Conceptualization, R.E., C.B. and M.F.; formal analysis, R.E. and C.B.; software, R.E. and C.B.; resources, J.D. and J.Z.; data curation, R.E., J.D. and J.Z.; writing--original draft preparation, R.E.; writing--review and editing, C.B., J.D., M.F. and J.Z.; visualization, R.E.; funding acquisition, C.B., M.F. and R.E. All authors have read and agreed to the published version of the manuscript.  
This research was funded through the Joint Polar Satellite System (JPSS) Proving Ground and Risk Reduction Program (PCRR). The publication costs were paid for by Science and Technology Corp.  
The authors thank the JPSS Proving Ground and Risk Reduction Program for fostering collaboration between product developers and data users to improve the research-to-operations feedback loop. [PERSON] made the initial connection between the authors' common research interests, which grew into this fruitful project. JPSS funded the dropsondes used in this project, and the authors are appreciative of [PERSON] and [PERSON] for their ongoing support of this effort. We thank Science and Technology Corp for funding publication costs, thereby supporting open access to scientific research. We also thank the three anonymous reviewers for their feedback, which helped improve the quality and clarity of this manuscript.