## 3 Results  
Within the framework of the abovementioned agreement with the Department of Civil Protection of the Italian Presidency of the Council of Ministers, IREA-CNR has collected an archive of airborne SAR data with the aim of generating multi-temporal, single-pass InSAR DEMs of the Stromboli volcano [77] to support the monitoring activities of the Department in this active volcanic area. To show the capabilities of the overall IREA-CNR airborne SAR infrastructure, we selected from this archive an X-band MIPS dataset acquired during the mission of September 2022. During this mission, the MIPS system was installed on board a Cessna 172 airplane operating at 2.5 km altitude with a mean velocity of 48 m/s. The departure/landing airport was located in Grumento Nova, Potenza, Basilicata region, southern Italy. The selected dataset consists of eight InSAR radar acquisitions carried out from eight straight tracks describing two concentric closed circuits surrounding the island (see Figure 10). It is remarked that, depending on the considered flight track, only a portion of the volcano is visible. Moreover, the shadow and layover effects [1] are particularly relevant due to the flight altitude, the radar look angles and the topographic height of Stromboli. To mitigate all these effects, we planned the two closed and concentric circuits shown in Figure 10. A set of 16 CRs was deployed near the departure/landing airport, since it was not possible to deploy them directly over the monitored area. Moreover, all the remaining ground segment activities described in Section 2.2.3 were accomplished. In the following, we show the main results achieved by applying the IREA-CNR SAR data processing chain described above to this specific dataset. Table 2 reports the main processing parameters set for the SAR focusing procedure and, subsequently, for the InSAR processing. Figure 11 reports the amplitude of one MLC relevant to the area where the CRs were deployed. In particular, eight CRs (highlighted by circles) are visible; the other eight CRs were, indeed, oriented in such a way to be visible in a radar acquisition carried out from a direction antiparallel to that considered in Figure 11. For the sake of brevity, the MLC (where the other eight CRs are visible) relevant to this anti-parallel track is not reported here. In any case, in both the corresponding SLCs, we measured the achieved geometric resolution for each imaged CR. The results are summarized in Table 3, where the CRs are clustered into two groups depending on their orientation (that is, depending on the SLC within which they are imaged). As it can be seen, the achieved resolution is very close to the theoretical resolution. For the sake of completeness, Figure 12 shows the azimuth (left panel) and range (right panel) cuts of the SLC amplitude image in correspondence with the CR highlighted by the green circle in Figure 11.  
Figure 10: Relevant to the Stromboli campaign: a pictorial view of the flown tracks (red lines) superimposed over a Google Earth orthophoto. With reference to the eight tracks shown in Figure 10, in Figures 13 and 14 we present some products of the IREA-CNR processing chain relevant to the four tracks of the internal circuit depicted in the figure. Similar results not shown here for brevity were also obtained for the other four acquisitions. In particular, Figure 13 reports the calibrated amplitudes of four MLC SAR images (one for each considered straight track). Figure 14 shows the corresponding modulo-\(2\pi\) interferograms (one for each considered straight track) achieved by removing the topographic contribution obtained from the external DEM exploited during the SAR focusing procedure. Specifically, the external DEM is a LiDAR-derived \begin{table}
\begin{tabular}{l c c c} \hline  & **SLC** & **MLC** \\ \hline Range pixel spacing [m] & 0.75 & 1.5 \\ Range resolution [m] & 0.75 & 1.5 \\ Azimuth pixel spacing [m] & 0.04 & 2 \\ Azimuth resolution [m] & 0.27 & 2 \\ \hline \end{tabular}
\end{table}