# Precipitation Products' Inter-Comparison over East and Southern Africa 1983-2017
## 1 Introduction
This is the context of the present analysis, of which the main objective is the inter-comparison of different satellite precipitation products taking into consideration both the climate and the precipitation seasonality of the regions of interest, and evaluating their ability to detect and quantify precipitation at different temporal scales. The study is focused on two regions of the African continent, East Africa (EA) and Southern Africa (SA), and covers the time period 1983-2017. Three daily 0.25\({}^{\circ}\) gridded satellite datasets were used: the Tropical Application of Meteorology using SATellite and ground based observation version 3 (TAMSAT3); the Climate Hazards group Infrared Precipitation with Stations version 2 (CHIRPS); and the Multi-Source Weighted-Ensemble Precipitation version 2.2 (MSWEP). Long-term satellite products such as those selected for this study are often used to monitor precipitation and evaluate its variability, trends, and linkages with other variables and phenomena able to drive precipitation through teleconnections, all information propaedeutic to a correct planning for water resource management. Nevertheless, results often depend on the specific satellite product under consideration, as demonstrated in [12] for a trend analysis over EA using Africa Rainfall Climatology (ARC) version 2, TAMSAT version 2, and CHIRPS. This is the reason behind this intercomparative study among a selection of the most advanced precipitation products exploited in studies focused on Africa. A correct interpretation of precipitation variability and trend results cannot overlook the differences and peculiarities of the satellite products. On the other hand, the availability of different satellite products must be considered as a powerful source of information that allows us to compare different retrieval methodologies, eventually choosing the most appropriate for the analyzed territory and interpreting the plurality of their estimates and application results as an estimate of the uncertainty range. Moreover, the choice of precipitation products based on different approaches (i.e., thermal infrared (TIR) versus merging of multi-source data including TIR, rain gauges, reanalysis, and passive microwave (PMW) estimates) gives also the opportunity to use a product exploiting PMW. Numerous studies in literature are focused on satellite product validation over Africa. Recently a pan-African validation of precipitation products (among which were MSWEP 2.1 and CHIRPS) for the period 1981-2016 was carried out by [PERSON] et al. [13], while [PERSON] et al. [14] evaluated the Integrated Multi-satellite Retrievals for GPM (IMERG) v04A and its predecessor the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA). The analyses performed by [PERSON] et al. [8] for CHIRPS, ARC, and TAMSAT version 2 and 3, and by [PERSON] et al. [15], who evaluated ARC, CHIRPS, TMPA, and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks Climate Data Record (PERSIANN-CDR), were specifically focused on East Africa. Again, TAMSAT3 was evaluated in SA [16] and CHIRPS and TAMSAT version 2 over Mozambique [17]. Among the validation studies on Africa, it is worth mentioning the work of [PERSON] et al. [18] over west Africa involving five gridded precipitation data sets, both ground- and satellite-based. Finally, [PERSON] et al. [19] validated 23 precipitation products over Western Africa, including those selected for this study, for a short period from 2000 to 2003 at daily and monthly scales. This represents the only example in the literature where the performances of the three selected products in their most recent versions have all been evaluated together to date. Thus, the present work intends to extend this product evaluation to a larger area, considering SA and EA, and to a longer time period, considering 35 years of data.