Evaluation of Reanalysis Temperature and Precipitation for the Andean Altiplano and Adjacent Cordilleras

Abstract

This study compares temperature, precipitation, and other climate variables from six widely used climate reanalysis products to inform ice-core climate proxy record calibration in the Altiplano region of the central Andes. The reanalyzes are the European Reanalysis version 5 (ERA5), European Reanalysis Interim, Modern-Era Retrospective analysis for Research and Applications (MERRA2), Japanese 55-year Reanalysis, Climate Forecast System Reanalysis and version 2 extension, and NCEP/NCAR Reanalysis version 1. These data products are validated against observations from automatic weather stations on the Quelccaya Ice Cap, Peru (5,650 m a.s.l) and Chacaltaya, Bolivia (5,238 m a.s.l), in addition to lower sites ranging in elevation 2,500–4,900 m a.s.l. Our results suggest that ERA5 provides the most robust overall depiction of temperature and precipitation across the study domain, and the data set is particularly useful for its back-extension to 1950. However, MERRA2 produces lower precipitation error scores owing to a gaged-based bias correction. An examination of ERA5 vertical atmospheric profiles for a latitudinal transect over Quelccaya shows considerable variability, including across major El Niño events, suggesting the need for caution when interpreting isotopic signatures in ice cores.