## 5 Numa Observations by GPM
### GPM-CO Precipitation Product Analysis
The selected 5047 DPR scan is also shown by the black dashed line. **(b)** Vertical cross-section of DPR Ku corrected reflectivity (Zc) for across-track scan 5047. The black dashed box highlights the bright-band. Comparing the GMI precipitation rate map in Figure 10 with the TBs at 37 GHz (Figure 7a,d), it is evident that lower TBs, found in the development phase compared to the mature phase, are due to the scattering by the ice hydrometeors in the convective cores (shown by DPR cross-section), which tends to mask the emission signal by the rain layers. For the GMI overpass on 18 November at 03:59 UTC, when Numa hits the coast of Southern Apulia region, the pattern of the precipitation (Figure 11a) follows the pattern of the TBs at 37 GHz (over the sea), with peaks around 14 mm/h in the region of minimum TBs at 89 GHz in the main rainband. DPR observations are not available for this overpass, because the storm is outside the Ku-band swath. However, a portion of the storm at this time lies within the field of view of the C-band Doppler dual polarization ground radar (GR) located in Pettinascura, Calabria region, managed by the Department of Civil Protection of Italy. Unfortunately, for this event only single polarization and Doppler radar volumes at 1 km radial resolution were available. The GPROF GMI rainfall rate, shown in Figure 11a, is compared with the rainfall rate estimated from the GR observations available at the time of the GMI overpass (Figure 11b). At this time the cyclone eye is 150 km from the radar site, and the radar shows portions of two rainbands, one of them closer to the radar site, which are fully observed by the GMI. Figure 11: Numa observation on 18 November. (**a**) Precipitation rate map estimated by the NASA GPROF CLIM algorithm from GMI overpass at 03:59 UTC. (**b**) Near-surface precipitation rate estimated from the GR scan in Pettinascura at 04:00 UTC using algorithms adopted by the radar rain mosaic product. The circle indicates the radar field-of-view (radius ~200 km), while the black dashed line indicates the 80\({}^{\circ}\) azimuth direction. Figure 10: GPM CO observation of Numa on 16 November 16 at 13:49 UTC. (**a**) Precipitation rate (mm h\({}^{-1}\)), estimated by the NASA GPROF CLIM algorithm from GMI observation. (**b**) Precipitation rate (mm h\({}^{-1}\)), estimated from Ku-band DPR observation. From the visual comparison of GPROF GMI and GR rain rate products shown in Figure 11, we note that the GMI rainfall rate estimate for the western rainband is in very good agreement with the GR rainfall rate estimate, showing values as high as 5 mm/h. However, we note a disagreement in terms of rainfall rate intensity for the eastern rainband (approximately centered at 39.5\({}^{\circ}\)N, 18\({}^{\circ}\)E), which appears to be more intense in the GPROF GMI products than that shown in the GR map. This discrepancy in the retrieved rain rate intensity could be explained by considering the slanted GR viewing geometry that constrains the GR near-surface bin height (NSBH) to progressively increase with the distance from the radar site. Thus, at longer distance the near-surface rain rate estimation is expected to be of lower quality. Figure 12 shows the GR perspective of the western and eastern rainbands positioned at \(\sim\)50 km and \(\sim\)120 km from the radar, with reflectivity factor peaks of the order of 30 dBZ and 20 dBZ, respectively. To compare more in detail GPROF GMI vs. GR, in Figure 12 the GMI TBs are superimposed to GR reflectivity. This comparison confirms that the eastern rainband, with larger TB depression at 166 GHz and 89 GHz (150 K and 210 K, respectively), corresponds to the radar raincell having larger vertical extension, but higher NSBH and lower GR rain rate. On the other hand, the western rainband, with smaller 166 GHz and 89 GHz TB depression (210 K and 240 K, respectively) shows a radar raincell with a smaller vertical extension but with lower NSBH and higher GR rain rate.