Evaluation of multiple reanalyses in reproducing the spatio‐temporal variability of temperature and precipitation indices over southern South America

BALMACEDA HUARTE, ROCIO; OLMO, MATIAS EZEQUIEL; BETTOLLI, MARIA LAURA; POGGI, MARIA MERCEDES

INTERNATIONAL JOURNAL OF CLIMATOLOGY

JOHN WILEY & SONS LTD

Año: 2021

0899-8418

Several temperature and precipitation indices, with special focus on extremes,were analysed in different sub-regions of southern South America during1979?2017 using multiple reanalyses, the CPC gridded data set and the mostextended network of meteorological stations employed in regional climatestudies up to date. Reanalyses generally well represented the spatial patternsof the indices, although they showed some differences in extreme indices overlarge portions of southern South America and tended to overestimate precipitationmaximums, especially in southern Chile. Furthermore, ERA-Interimpresented clear difficulties in reproducing precipitation near the Andes Mountains,exhibiting the largest overestimations. This seemed to be improved inthe new generation of ERA reanalyses (ERA5). When evaluating the long-termchanges, most of the data sets agreed in general warming conditions, strongerand more homogeneous for the maximum temperature. NCEP1 and NCEP2reanalyses showed contrary temporal changes in almost all the temperatureindices. Precipitation indices exhibited less consistent changes amongreanalyses, although significant upward trends were detected for precipitationextremes in southeastern South America and downward trends were detectedin southern Chile in the observational data sets. In addition, most of the datasets agreed in drier conditions in the arid diagonal region of Argentina asreflected by significant positive trends for dry spells and negative trends for thetotal annual precipitation. In terms of the inter-annual correspondence,reanalyses usually presented good correlations to the stations reference in theregional averaged series, mainly for temperature indices and more variable forprecipitation indices. Overall, no reanalysis was found to perform best. Theuse of reanalyses data to perform regional climate studies should consider theexistent differences among them and with observational data. Moreover, usingmultiple sources of information is strongly recommended to account for observationaluncertainty, especially in regions like southern South America, wheredata availability and its resolution are often limited.