# Hailstorm Detection by Satellite Microwave Radiometers
## 6 Summary and Conclusions  
A new model for hail detection based on satellite PMW radiometers has been presented. By using the MicroWave Cloud Classification (MWCC) method only deep convective clouds were selected to isolate hail signatures. In order to reproduce the signal attenuation due to hail scattering a probabilistic method was adopted for describing the TB reductions as a function of hail diameters. The carrying capacity concept was used to force the convergence of the model when saturation conditions are reached. The result is a simple one-variable (TB150) equation that calculates the probability associated with the presence of hail by identifying large and very large hail signatures. The validation with 12-year matchup data demonstrates the high performance of the model in detecting hail by showing strong correlation with validating dataset and reproducing well the seasonality of hailstorms over CONUS.  
The MWCC-Hail model is now applied in investigating the presence of hail patterns during deep convection over mid-latitude and tropical regions where the majority of heavy rainstorms are typically due to the melting of large ice hydrometeors (graupel and hail) before reaching the ground. The investigation of hail amounts in convective rain both in terms of size and occurrences  
Figure 13: MWCC-Hail applied to the GPM constellation during two severe hailstorms. The hail probability is calculated during heavy hailstorms with (**a**) GMI frequencies on 5 September 2015 over Naples, and on 10 Jul 2019 over the Adriatic Sea coast with (**b**) F17-SSMIS, (**c**) N20-ATMS, and (**d**) N19-MHS, respectively.  
is instrumental to a better understanding of the impact of frozen hydrometeors in inducing extreme rainfalls in view of confirming the hypothesis of severe storms increase due to climate change. In this perspective, the MWCC-Hail model has been integrated in the computational scheme of the water vapor strong lines at 183 GHz (183-WSL) algorithm [4] to associate hail probability with precipitation retrievals so that the incidence of hail in the formation of heavy rain can be evaluated.  
The flexibility of the hail detection model MWCC-Hail stimulated further applications to the GPM constellation, where MHS-like radiometers currently orbit, showing very high performances in detecting hail patterns. The first results presented here have motivated a new sensitivity analysis to evaluate the generalization of the model to the new radiometers by assessing the impact of MHS-like frequencies of PMW radiometers orbiting of the GPM constellation (ATMS ch17: 165.5 GHz; GMI ch11: 166.5 GHz). This opens the way to the applicability of the MWCC-Hail at the global scale for building a satellite-based worldwide hail climatology.  
We conclude that the potential offered by the hail detection model discussed in this work in terms of its generalization to all MHS-like radiometers encourages further studies of a geostationary high-frequency PMW sensor. Such instrument is under discussion since almost 20 years within the international satellite community. This challenging mission will definitely change the current prospective of the atmospheric studies introducing the possibility to continuously observe meteorological phenomena impacting the hydrologic cycle.  
[PERSON] conceived the method and carried out the data analysis. [PERSON] contributed to the concept. [PERSON] and [PERSON] contributed to the validation. All authors contributed to the writing. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
This work is performed in the context of the scientific cooperation defined by the MOU between the Institute of Atmospheric Sciences and Climate of the Italian National Research Council (CNR-ISAC) and the National Oceanic and Atmospheric Administration (NOAA). [PERSON] is gratefully acknowledged for drawing Figures 1, 12 and 13.  
The authors declare no conflict of interest.