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<p>In recent decades, snowfalls, snow cover and duration over Central Italy have decreased and there have been some extreme snowfall events followed by extreme avalanche activities. In this regard, the Calderone Glacier (hereinafter Calderone) represents a geographical and geomorphological element of great interest and is defined as a sentinel of climate change in central Italy, as it is going through a strong phase of reduction: fragmented into 2 glacierets since the end of the last century, it is the only glacial area in the Apennines, and the southernmost in Europe, and for its position on the summit of the Italian Gran Sasso (2912 m asl), a mountain group located in the center of the Apennine belt in the Mediterranean area.</p> <p>The Italian Glaciological Committee (Comitato Glaciologico Italiano (CGI) every year with ad hoc in-situ inspections in early autumn monitor the Calderone mass balance. The mass balance of a glacier depends on the interplay between the mass gains and losses promoted by climate and those associated by the inherent flux; its monitoring is essential because it can contribute to the knowledge of the current ongoing evolution of glaciers.</p> <p>Continuation of the traditional type of monitoring, like the one performed by CGI, based on direct measurements of accumulation and ablation by means of a network of stakes, appears to be an unlikely prospect, because in-situ data gathering usually implies expensive field campaigns and with difficult access to the sites, resulting in limited spatial and temporal resolution. In contrast, techniques based on remotely sensed data, among several techniques, those relying on Synthetic Aperture Radar (SAR) demonstrated to be very effective due to the instrument’s capability of operating day and night independently of the weather conditions.</p> <p>Differential interferometry or DInSAR can be used to estimate displacements, but due the slow-changing nature of glacier masses and the consequent temporal distance necessary to appreciate changes between two dates, DInSAR technique, in such evaluation conditions, suffers from generally low coherence values, which generally prevent accurate estimates. </p> <p>For such a reason, in this work we propose to estimate the mass balance for the Calderone through the displacement maps obtained from the difference between two Digital Elevation Models (DEM) obtained from the processing of COSMO-Skymed X band data. Each DEM is obtained from adjacent dates (w.r.t. products availability), and their generation is less subject to the low-coherence problem. In this way two DEMs, whose temporal distance is about 12 months, can be subtracted to obtain displacement maps that are subsequently compared with CGI in-situ measurements for the winter periods from 2010 to 2022. The data used in this study consist of COSMO-SkyMed satellite X-band single-look complex images in slant geometry (level 1A), Stripmap Himage mode (HH polarization) at 3m of spatial resolution. Processing includes, in addition to a canonical DEM generation process, a specific part focused on obtaining the average values, active area and total area for the calculation of the mass balance.</p> <p>Preliminary results will be illustrated and discussed, pointing out potential developments and critical issues.</p>

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<p>The Apennine mountain range is the backbone of the Italian peninsula, crossing it from North-West to South-East for approximately 1200 km. The main peaks are found in Central Apennines, especially in the Gran Sasso d’Italia massif, which hosts the highest Apennines peak, named Corno Grande, with its 2912 m a.s.l. During the winter season, Central Apennines are typically covered with snow, with thickness that can vary between a few centimeters to several meters. Despite the historical presence of snow in these territories, the Apennine snowpack is poorly studied and weather data coming from automatic measurement stations and manual snow measurements hardly coexist. Thus, within the SMIVIA (Snow-mantle Modeling, Inversion and Validation using multi-frequency multi-mission InSAR in Central Apennines) project, we identified the measurement sites of Pietrattina, at 1459 m a.s.l, and Campo Felice, at 1545 m a.s.l., both located in Central Apennines. There we collected automatic measurements using ad hoc installed automatic weather-snow stations (AWSS) and where we performed systematic manual measurements of the snowpack properties, from November 2020 till April 2021. The AWSS measures every 5 minutes air temperature, relative humidity, wind speed, wind direction, incoming short-wave radiation, reflected short-wave radiation, soil surface temperature, snow surface temperature and snow height. The manual part of the campaign included the digging of 10 and 8 snow pits at Pietrattina and Campo Felice sites, respectively, to measure vertical profiles of snow density, temperature, grain shape, grain size and fractional content of light absorbing impurities. Manual snow measurements provide important information on the state of the snowpack, and give the opportunity to reconstruct the history of the snowpack. Their proximity to automatic weather stations let us evaluate the impact of the very local atmospheric conditions on the snowpack evolution. These measurements were performed within the SMIVIA project to: i) evaluate the ability of the snow cover model SNOWPACK to reproduce the observed snow cover properties; ii) verify the possibility to infer snow height and snow water equivalent from the data retrieved with Earth observation satellites; iii) investigate whether the use of a combination of snow numerical models and remote sensing data may provide better results compared to using each of the aforementioned approach, separately. Nevertheless, the data collected during the SMIVIA campaign at the measurement sites of Pietrattina and Campo Felice during season 2020-2021 can also provide precious information for other fields of study, like hydrology, biology and chemistry.</p>