Mountain waves forcing deep convection at the East of the highest Andes tops

R. HIERRO; H. PESSANO; P. LLAMEDO; A. DE LA TORRE; A. ODIARD; P. ALEXANDER

Congreso; 7th European Conference on Severe Storms; 2013

In this work we analyze a sample of 400 storm cases, between 2004 and 2011, that produced a considerable damage to cultivated areas at the North of Mendoza, Argentina. This orographic semiarid region at midlatitudes (roughly between 32S and 36S) at the East of the Andes constitutes a natural laboratory where usually diverse sources of gravity waves take place. From WRF model simulations, radar network and radiosounding data, the lifting mechanism required to raise air parcels to levels of free convection, partially supplied by mountain waves (MWs), is analyzed. Based on a previous work, a criterium for the significant presence of MWs is established. Near 30% of the analyzed cases exhibited MW structures during the storm events. Stability conditions in the presence of MWs are evaluated from convective available potential energy (CAPE) and convective inhibition (CIN) indices. The energy provided by MWs is compared with the necessary to trigger convection. A Morlet Continuous Wavelet Transform along zonal and meridional direction is applied to vertical air velocity to isolate parameters belonging to dominant stationary MW modes. Specific features between radar data and dynamic processes found for this sample, with and without significant MWs, are discussed.