How do GCMs represent daily maximum and minimum temperatures in La Plata Basin?

BETTOLLI, MARÍA LAURA; PENALBA, OLGA CLORINDA; KRIEGER, PABLO ANDRÉS

Cancun

Conferencia; AGU Meeting of the Americas; 2013

This work focuses on southern La Plata Basin region which is one of the most importantagriculture and hydropower producing regions worldwide. Extreme climate events such as cold and heat waves and frost events have a significant socio-economic impact.It is a big challenge for global climate models (GCMs) to simulate regional patterns, temporal variations and distribution of temperature in a daily basis. Taking into account the present and future relevance of the region for the economy of the countries involved, it is very important to analyze maximum and minimum temperatures for model evaluation and development. This kind of study is aslo the basis for a great deal of the statistical downscaling methods in a climate change context.The aim of this study is to analyze the ability of the GCMs to reproduce the observed daily maximum and minimum temperatures in the southern La Plata Basin region. To this end, daily fields of maximum and minimum temperatures from a set of 15 GCMs were used. The outputs corresponding to the historical experiment for the reference period 1979-1999 were obtained from the WCRP CMIP5 (World Climate Research Programme Coupled Model Intercomparison Project Phase 5).In order to compare daily temperature values in the southern La Plata Basin region as generated by GCMs to those derived from observations, daily maximum and minimum temperatures were used from the gridded dataset generated by the Claris LPB Project (?A Europe-South America Network for Climate Change Assessment and Impact Studies in La Plata Basin?). Additionally, reference station data was included in the study. The analysis was focused on austral winter (June, July, August) and summer (December, January, February).The study was carried out by analyzing the performance of the 15 GCMs , as well as their ensemble mean, in simulating the probability distribution function (pdf) of maximum and minimum temperatures which include mean values, variability, skewness, et c, and regional patterns. The results indicate that models are able to reproduce the full range of summer and winter maximum and minimum temperature values, although the intermodel dispersion is high. Most models reproduce fairly well the differences between daily summer and daily winter temperature distributions, however GCMs tend to smooth the extreme values. The largest differencesare found for winter minimum temperature values.