Comparison of Data from Rain Gauges and the IMERG Product to Analyse Precipitation in Mountain Areas of Central Italy  
[PERSON]  
1 School of Science and Technology, Geology Division, University of Camerino, 62032 Camerino, Italy; [EMAIL_ADDRESS] (M.B.); [PERSON] (M.M.); [EMAIL_ADDRESS] (G.P.)  
[PERSON]  
1 School of Science and Technology, Geology Division, University of Camerino, 62032 Camerino, Italy; [EMAIL_ADDRESS] (M.B.); [PERSON] (M.M.); [EMAIL_ADDRESS] (G.P.)  
[PERSON]  
2 School of Earth, Atmosphere and Environment, Monash University, Melbourne 3800, Australia; [EMAIL_ADDRESS]  
[PERSON]  
1 School of Science and Technology, Geology Division, University of Camerino, 62032 Camerino, Italy; [EMAIL_ADDRESS] (M.B.); [PERSON] (M.M.); [EMAIL_ADDRESS] (G.P.)  
[PERSON]  
1 School of Science and Technology, Geology Division, University of Camerino, 62032 Camerino, Italy; [EMAIL_ADDRESS] (M.B.); [EMAIL_ADDRESS] (M.M.); [EMAIL_ADDRESS] (G.P.)  
Footnote  
very important to determine snowfall, both for the assessment of groundwater recharge and for the subsistence or possible existence of ski facilities [8]. Recently, increasingly accurate and reliable data are becoming available from algorithms that interpret satellite images. A new programme based on the Global Precipitation Measurement (GPM) satellite constellation was launched in 2014 and uses the Integrated Multi-satellite Retrievals for GPM (IMERG) algorithm to obtain the most correct precipitation values possible. As a result, many researchers rely directly on the use of satellite data to estimate precipitation in a given area [9; 10]. However, IMERG data are much more often calibrated using data from reference weather stations, appropriately validated by analysing the reliability of the satellite product [11]. Thus, it seems that field measurements still allow for greater accuracy where available and especially are measurements at the precise point of interest; in addition, weather stations provide the collection of other climate variables that could not otherwise be estimated without them. In some places, satellite data are used instead of rain gauges due to the poor reliability of the latter and because of the lack of them [12]. In some cases, attempts have been made to assess the differences between mountain rain gauges and satellite observations [13]; it is usual for the current literature to make an assumption regarding the reliability of rain gauges, which is not always correct, and therefore deserves to be studied in order to resolve any measurement errors. As a result, the current state-of-the-art is ambiguous with regard to an accurate understanding of the problems of rain gauges in high mountain weather stations or possible discrepancies in satellite data [14; 15]. Furthermore, in order to better assess the reliability of satellite estimates and rain gauges, it would be very important to perform interpolations, taking into account validated and reliable rain gauges, even if they have a lower altitude. In one study, the performance of satellite data, improved through the use of interpolation, was evaluated in order to achieve better levels of accuracy of precipitation data [16]. To conclude, the current state of the literature leaves unsolved problems in the case of mountain environments, both with regard to the correct estimation of precipitation by rain gauges and with regard to the reliability of satellite products for measuring rainfall. In this context, the present study has the ambitious objective of solving the problems affecting mountain rain gauges and IMERG data, evaluating the possible underestimation of both altitude-based interpolations and possible climatic variables at the same weather station investigated. The aim is to be able to better quantify rainfall by assessing any errors that plague rain gauges or satellite data in the mountainous areas of central Italy in order to provide a reliable estimate and a method of interpretation for future analysis in these environments.