Regional climate of Southern Central Andes region from different gridded datasets and CMIP5 models

RUSTICUCCI MATILDE; ZAZULIE NATALIA; RAGA, GRACIELA B.

Montevideo

Conferencia; WCRP Conference for Latin America and the Caribbean: Developing, linking and applying climate knowledge.; 2014

World Climate Research Programme

In the southern central Andes region, yearly snowfall and mountain glaciers are vital sources of fresh water that contribute to the sustainability of socio-economic activities in nearby populations. Snowpack melt is the main source of summer stream flow of rivers so they affect human consumption, irrigation, hydropower and industries. The lack of meteorological information over the Andes has always been an issue when carrying out climatic studies in the region. In the last three decades the National Weather Services from Argentina and Chile have closed a considerable number of meteorological stations in the region. From the decade of 1990 a national effort from Argentina (through the Subsecretaría de Recursos Hídricos) has been made to monitor hydrological resources over the country. A number of meteorological and hydrological stations have been installed in river courses. At elevated sites, some stations were located but only measuring snow water equivalent from the snow pillow replacing previous direct snow measurements. Although these improvements in the number of stations are useful there is still a poor coverage of the region due to the complex terrain and there is still a need of elevated meteorological stations. In order to overcome this problem and to understand the long-term variability in the region, monthly gridded datasets are compared for southern South America region with reanalysis data from the ECMWF also known as ERA-Interim. We used the most recent version of six datasets including gridded in-situ observations (Climate Research Unit, Global Precipitation Climatology Centre, University of Delaware), merged satellite and in-situ data (Global Precipitation Climatology Project), satellite estimates (Tropical Rainfall Measuring Mission) and reanalysis (ERA-Interim). All datasets present an adequate representation of both mean winter and summer precipitation over subtropical South America. GPCC shows a better representation of winter precipitation in the southern central Andes region. For the period 1961-2010 negative trends on the west side of the Andes and positive trends on the east side from GPCC are found. When the period 1979-2010 is considered a generalized negative trend is found in the southern central Andes from GPCC and ERA-Interim. In addition a subset of coupled models from the CMIP5 project was selected to evaluate their performance over the studied region. In order to have a good regional representation over the southern central Andes area, 10 models that satisfied the condition of having a resolution of 1.5º degree or less were selected. The same aforementioned analysis was applied to the individual models and the ensemble mean.