# A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation
## 3 Study Cases
### Application 5: Precipitations in the Mediterranean Basin  
The Mediterranean basin was defined as a \"hot-spot\" by [226], being one of the most responsive regions to climate changes. Different global and local scale studies agree on both a rainfall decrease and a growing trend of the minimum and maximum temperatures (e.g., [227; 228; 229]). Models also foresee long dry periods, interrupted by extreme intense summer precipitations, increasing flooding risks (e.g., [230]). Therefore, ameliorating the quality and quantity of the monitoring network represents an asset in order to reduce the effects, and the damages, of extreme weather events.  
Precipitation is one of the key measurements, but it is also extremely hard to access the space and time scales of interest and/or because of the complexity or inaccessibility of the studied area (e.g., [231]). Although ground-based weather radars allow to monitor precipitation variability, they are not uniformly and/or sufficiently densely distributed, and gaps for monitoring cloud dynamics on large vertical extension can be filled only by remote sensing observations (e.g., [232]). The Italian Constellation of small satellites for Mediterranean basin Observation (COSMO-SkyMed), First and Second Generations, are medium-large satellites equipped with SAR instrumentations for EO-focused disaster monitoring, including the one caused by flooding [233; 234]. Precipitation measurements in the Mediterranean region are currently limited to just a few missions [235], such as the Global Precipitation Measurement mission (GPM) and TRMM, both being large satellites (e.g., [236; 237; 238; 239]). In the last few years, the advacement in the miniaturization technology for space instruments has made small satellites an alternative to the larger ones [240]. In particular, CubeSats, such as the NASA Earth Science Technology Office RainCube, TEMPEST-D, and TROPICS, have been developed with specific meteorological goals [51; 65; 241; 242]. Such missions provided useful information on storm structure and distribution, but their high-cost infrastructures are not counterbalanced by a satisfactory scientific return in terms of data temporal resolution for a continuous and real-time characterization of the fast-changing vertical structure of convective cells (e.g., [243; 244; 245; 246]). Constellations of small satellites (e.g., NASA CYGNSS) could be a cost-effective solution that can provides meteorologica data with high temporal sampling [247].  
Remote sensing payloads suitable to measure the precipitation distribution host a Ka band radar (e.g., [248]). The monitoring of the rainfall in the Mediterranean area can be ensured by a Ka (35.75 GHz) weather radar, with a horizontal resolution of 5 km (or better), a time resolution of 30 min (or better), a vertical resolution of 250 m, and a sensitivity of 20 dBZ. Such requirements are consistent with time and spatial scales of thunderstorm cloud formation (from early to decaying stage) (e.g., [244]). It is necessary to rely on a swath of 500 km and a maximum speed at ground of 5 km/s on a low Earth orbit. Thus, a dense constellation of mini-satellites providing high revisiting times in the entire Mediterranean area could be an effective and less expensive alternative to the current missions.  
A typical output of this application consists of reflectivity measurements collected at different altitudes within the tropospheric columns, called the Vertical Profile of Reflectivity (VPR) (e.g., [249]). A quality control chain is needed to remove random and systematic errors, including the correction of the vertical reflectivity profiles (i.e., removal of bright band effects), and the mitigation of attenuation along the path (e.g., [250; 251; 252]). This quality control procedure is propaedeutic for a proper validation of the measures, performed through reflectivity data collected by traditional ground-based weather radar, and for a real time application inherent to the monitoring of precipitation events.