Validation of CHIRPS precipitation dataset along the Central Andes of Argentina

A validation covering a 30-year period (1987-2016) of the relatively new CHIRPS precipitation dataset was performed over the Central Andes of Argentina (CAA), a semi-arid region with complex topography and sparse ground observations. Precipitation data from 57 rain gauges and several well-known continuous and categorical validation statistics were assessed to evaluate the performance of CHIRPS estimations. The study area was divided into two zones based on the timing of the rainy season maximum, in order to determine regional differences in the characterization of precipitation patterns. The results of this study indicate that CHIRPS data reproduce adequately several characteristics of precipitation along the study area, as the seasonal and interannual variability and the spatial patterns of precipitation. CHIRPS dataset is able to capture the rainy season characteristics over the CAA, considering the Mediterranean climate features over the Andes ranges and the monsoonal regime in the lowlands. CHIRPS achieves better results for the stations located in the region with summer precipitation maximum, mostly located over Cuyo region (correlation = 0.86, bias = 11%, mean absolute error = 15.3 mm). Despite the strong correlation of 0.82 over Northern Patagonia region, CHIRPS showed a significant overestimation of the seasonal precipitation totals during the cold semester (April to September, bias = 65.8%, mean absolute error = 34.7 mm). These systematic errors can be attributed to the poor performance of CHIRPS in reproducing the precipitation features over the zones above 1000 m.a.s.l. One of the reasons behind the observed differences can be attributed to the limited number of anchor stations used in the CHIRPS calculation procedure, which highlights this study as an independent validation given the amount of meteorological stations used.