# Passive Microwave Imagers, Their Applications, and Benefits: A Review
## 4 Summary of Survey and Discussion  
As part of this report, an expert survey was conducted to assess the value of PMWIs. According to [PERSON] et al., surveys are an excellent tool for gathering insights into the value of satellite observations, in this case, from PMWIs [152]. This survey consisted of 12 questions, 9 of which were related to the relevance and impact of PMWI data; these questions can be found in the Appendix A. Conducting this survey allowed for a further understanding of the applications of PMWI data, the impact related to the products created from its utilization, and their limitations and necessary improvements for future PMWIs. The survey was sent to 87 expert users of PMWI data and people in the fields of meteorology, hydrology, remote sensing, etc. Unfortunately, only nine experts completed the survey, and the main findings of this survey are presented below. Through this survey, it was found that the respondents' main uses for these data were for hurricane tracking and precipitation monitoring. Other applications included ocean surface wind measurements, structure monitoring and rapid intensification signals, and operational multi-satellite water vapor product development for forecasters. The main precipitation-related uses of these data found through this survey include the following: precipitation estimation, precipitation classification using machine learning, the development of Level 2 (L2) and Level 3 (L3) precipitation rate and accumulation products, the development of precipitable water products, advected total precipitable water estimates, advected layer precipitable water estimates, the development of blended total precipitable water products, and the development of blended rain rate products. The TC-related uses include the development of TC PRIMED [50], studying the intensity change and structure of TCs, and locating the center of TCs. It was also specifically mentioned that the National Hurricane Center (NHC) uses PMWIs to examine the structure of TCs. Another use for these data mentioned in the survey responses includes weather forecasting for the aviation, marine, and public sectors, from regular daily forecasts to issuing watches and warnings. Finally, one of the responses mentioned that these data are especially useful for studying open ocean storms and when reconnaissance aircraft data are unavailable. When asked to rank the importance of PMWI data in their respective applications from 1 to 10, with 10 being extremely important, 67% ranked the importance at 10, 22% ranked it at 9, and 11% ranked it at 7. This leads to the conclusion that these data are extremely important for these applications. The survey respondents were also asked to describe and quantify the impact of their work using PMWIs. The majority of the responses were related to the capability of improving forecasts using these data. Specifically, a large number of the respondents mentioned that by using these data to improve forecasts of TCs, forecasters can have more confidence when predicting rapid intensification. Furthermore, when improving NHC forecasts utilizing PMWI data, more accurate tropical storm and hurricane watches and warnings can be issued, thus reducing the damage to infrastructure, property, and people's lives. One of the respondents also mentioned that these data are used to predict flooding events; using these data, more accurate warnings of flooding threats can be issued. One respondent noted that in the past decade, improved forecasts had saved naval bases approximately USD 54 million per event; however, a supporting reference for this value was not provided. Survey respondents were also asked to discuss the limitations of PMWI data and make suggestions for their improvement. The primary limitations that the respondents found from these data are the temporal coverage and resolution. They emphasized that the amount of satellite passes and the data latency are significant limitations that should be improved. A respondent also specifically emphasized the infrequent overpasses over TCs.