The role of atmospheric forcings and WRF physical set-up on convective initiation over Córdoba, Argentina

ALVAREZ IMAZ, MILAGROS; SALIO, PAOLA; DILLON, MARÍA EUGENIA; FITA, LLUÍS

ATMOSPHERIC RESEARCH

ELSEVIER SCIENCE INC

Año: 2020

0169-8095

The accurate determination of the location and timing of convective initiation (CI) is a crucial aspect of forecasting and high impact weather warning systems associated with deep convection. Central Argentina, particularly the Sierras de Cordoba ´ (SDC), is characterized by the regular occurrence of deep convective cells thatreach supercell characteristics producing large hail and occasionally tornadoes.In order to analyze the sensitivity of the CI over SDC, an ensemble of 12 simulations with the WRF model atconvection-permitting resolution (3 km.) was carried out to study a marginal supercell initiated on October 17,2017 at the SDC foothills. The ensemble was built using 3 different microphysics (MP) parameterizations (WSM6,Thompson and Morrison) and 2 planetary boundary layer (PBL) parameterizations (Yonsei University and MellorYamada Janjic). Also, the sensitivity of initial and boundary conditions is considered by forcing the model with 2different global analyses: the European Centre for Medium-Range Weather Forecast (ECMWF) model, and theGlobal Data Assimilation System (GDAS).The two different forcing data show low-level moisture differences, which later modulate the life-cycle of thesimulated cells. A tracking algorithm was used to capture their life-cycle, and CI was detected at both the hillsand the plains. Simulations forced with ECMWF analyses tend to show better results with characteristics closer tothe ones observed including: initiation over the eastward slope of SDC, stronger cells and slow propagation.Among all simulations analyzed, the best performance was obtained with the combination of Thompson MP andYonsei University PBL schemes.