Downslope winds on Eastern Slopes of the Central Andes mountains of South America in a 20-yr climate simulation with the ETA Model

PABLO L. ANTICO; SIN CHAN CHOU; CAROLINE MOURÃO

Sao Jose dos Campos

Workshop; V Worketa - V Workshop em Modelagem Numérica de Tempo e Clima em Mesoescala utilizando o Modelo Eta: Aspectos Físicos e Numéricos; 2016

Instituo Nacional de Pesquisas Espaciais

P { margin-bottom: 0.21cm; }TheZonda wind is a local version of the alpine foehn in the centralAndes mountains in South America. It blows on the eastern slopes andproduces an extremely warm and dry condition in Argentina. In thisstudy, the occurrence of Zonda wind events during a 20-yr simulationfrom the regional Eta model is analyzed and results are compared toprevious studies of Zonda wind events based on weather observations.We define a set of parameters to account for the zonal pressuregradient across the mountain, vertical movement and air humiditytypical of Zonda wind events. These parameters are applied tocharacterize Zonda wind events in model run and to classify them assurface-level or high-level episodes.Theresulting annual distribution of Zonda occurrences based on compositeanalyses shows a preference for winter and spring with rareoccurrences during summer. For the surface?level Zonda wind events,the highest frequency occurs during spring. Whereas surface?levelZonda wind episodes more commonly initiate in the afternoon,high?level Zonda wind events show no preference for a giveninitiation time. Our results are mostly in agreement with previousobservational results.