Novel Polarimetric Radar Observations of Upscale Convective Growth near the Sierras de Córdoba

Satellite observations have revealed that some of the world’s most intense deep, moist convective storms occur across subtropical South America. This convection has been linked to severe weather production in the form of damaging straight-line wind gusts, large hail, and/or tornadoes across regions such as Central Argentina. The satellite data fail to reveal the time evolution of these storms, however, and thus, how convective mode and evolution relates to the extreme intensity. This research is particularly interested in how isolated convection, initiated across the higher terrain of the Sierras de Córdoba in Argentina, South America, transitions to relatively larger mesoscale convective systems, and how such “upscale convective growth” relates to severe weather production/severity.

A C-band, dual-polarization radar has recently been implemented in Córdoba, Argentina (2014), allowing for the first suite of high-resolution storm imagery in this region of South America. Radar fields, such as reflectivity and radial velocity, are utilized to characterize features of convection over a 1˚ x 1˚ domain centered on the Córdoba radar site. A total of 46 cases were selected between 2015-2017 documenting different storm morphologies. Selected cases were grouped by convective mode (i.e., discrete vs. multicell), initiation location/time, time between initiation and upscale convective growth (if any), among others. Preliminary results indicate that 8 (17%) of the events that were analyzed were characterized as discrete-supercell, 13 (28%) as discrete-non-supercell, 8 (17%) as multicell-organized (e.g., MCS), and 17 (38%) as multicell-unorganized. Common radar attributes, such as reflectivity hook echoes and radar finelines, are common features documented with incipient convection. Additionally, environmental characteristics for the different pathways of upscale convective growth are analyzed using NCEP and ERA-Interim reanalysis. These analyses are in preparation for the RELAMPAGO (Remote sensing of Electrification, Lighting, And Mesoscale/microscale Processes with Adaptive Ground Observations intensive observing period (1 November – 15 December 2018; more information available at https://publish.illinois.edu/relampago/) in west-central Argentina, South America.