Future Change of Wet Days in the Central and Southern Peruvian Andes during Austral Summer Using CMIP5 Models

Climate change is one essential factor of water resource in the Tropical Andes. Climate change will modify the intensity, probability, and spatial pattern of wet days. However, there are no studies for central Peruvian Andes (Mantaro basin, MB) and Peruvian Altiplano (Puno) during austral summer (December-March). To assess that, we used several reanalysis (ERA-Interim and MERRA2) and CMIP5 simulations (Historical, RCP4.5, and RCP8.5). The primary tool is the bias correction technique called Cumulative Distribution Function-transform (CDF-t).

For MB, uncorrected and corrected data present an increase of the probability of wet days under the RCP4.5 and RCP8.5 scenarios. This increment is related to a west-east gradient, which is stronger in the RCP4.5 scenario. Spatially, rainfall over western Cordillera and MB present same intensity than in the eastern lowland. It agrees with a strengthening of the variance of precipitation from December to February while it registers a reduction in March. Concerning Puno, uncorrected and corrected data present an increase of the probability of wet days over the eastern side of Lake Titicaca and northwestern part of Puno under the RCP4.5 and RCP8.5 scenarios. Spatially, rainfall over the northern region of Puno features a southward shift toward 15.2ºS under RCP4.5 and RCP8.5 scenarios. Moreover, the results also show a strengthening of the variance of the precipitation in December, reduction in March and mixing in January and February.

All these results will serve as input for the current adaptation policy of water resource in Peruvian Andes.