Validation of atmospheric circulation in CMIP5 GCMS over Southern South America

HUTH, R; STRYHAL, J; POGGI, M MERCEDES; BETTOLLI MARIA LAURA

Sydney

Conferencia; AMOS-ICSHMO 2018; 2018

AMS

Global Circulation Models (GCMs) are fundamental tools for climate studies and provide the initial information for the generation of regional climate change scenarios through dynamical and/or statistical downscaling. The basic assumption of applying downscaling methods is that the main drivers of local climate conditions are credibly simulated by GCMs. In this context, this study aims at evaluating the skill of a set of CMIP5 GCMs in representing circulation types in Southern South America. To this end, we test the ability of GCMs to reproduce sea level pressure patterns using several classification methods, including rotated principal component analysis in a T-mode, several implementations of cluster analysis, Jenkinson-Collison scheme, Lund?s correlation method, and circulation prototypes. Several reanalysis datasets are taken as reference. Taking into account the characteristics of the regional circulation at low levels, the validation analysis is performed in different domains: a large domain covering part of the Pacific and Atlantic oceans and the Andes mountain range that influence the structure of the circulation and positioning of the synoptic systems; and a domain covering southeastern South America where meridional circulation is responsible for the moisture advection at low levels from the Amazonia to mid-latitudes and incursions of both polar and tropical air masses, bordering the Andes. This evaluation is performed in the framework of the CORDEX Flagship Pilot Study initiative in southeastern South America, which uses both dynamical and statistical downscaling approaches to provide high-resolution information over the region with specific focus on extreme precipitation events.