Influence of Terrain and Environment on Cold Pools during RELAMPAGO

Convectively-generated cold pools are an important component of the convective lifecycle via the generation (and inhibition) of new deep convection. Cold pool characteristics such as depth and propagation speed play a large role in determining secondary convection, however the controls on these characteristics imparted by the other convective components (i.e. updrafts and downdrafts) and ultimately the environment is still not completely understood. Modification of the convective components is also achieved by microphysical processes, and previous studies have been inconclusive regarding the most important hydrometeor and associated latent cooling within downdrafts influencing the cold pool, adding ambiguity to the aforementioned controls. Further ambiguity is added by the influences of terrain on the mesoscale environment, convective dynamics, and storm microphysics, which are also not well understood.

This study exploits data collected during the Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) field campaign to address these knowledge gaps, and ultimately to improve the parameterized and explicit representations of deep convection in weather and climate models, especially in areas of complex terrain. RELAMPAGO was conducted in Argentina from 1 November – 16 December 2018, in the vicinity of the Sierras de Córdoba mountain range and in the foothills of the Andes mountains. During 19 intensive observing periods (IOPs), a variety of convective storm events were observed using mobile and fixed Doppler radars, surface based in-situ instrumentation, and aircraft (in tandem with the Clouds, Aerosols, and Complex Terrain Interactions (CACTI) campaign). This study uses measurements from 10 IOPs to quantify the relationship between environmental variables and cold pools, with additional considerations of the terrain and microphysical processes. The highly adaptive observing strategies during RELAMPAGO allowed for targeted soundings within the cold pool as well as high-resolution mobile radar scans to observe cold pool structure. Specific attention will be paid to cold pool depth and intensity across locations in the high terrain through the plains. Additionally, high-resolution, idealized numerical simulations initialized with observed soundings will be used in an attempt to separate out the respective influences of complex terrain and storm microphysics on the cold pools and convective lifecycle.