Effects of Sea Breezes and Cold Pools on Convective Evolution during TRACER

Description

The coastal urban environment of southeastern Texas features several different phenomena that may assist in triggering convective storm formation. This study focuses on the separate and combined roles of two such phenomena: sea-breeze flows (from the Gulf of Mexico and Galveston Bay) and low-level convective outflows (cold pools). Sea breezes and cold pools both feature cool, dense airmasses advancing into warmer regions. The advancing cool air wedges beneath a preexisting warm airmass, providing a lifting mechanism that can initiate or maintain convective updrafts. Both phenomena may alter local moisture, stability, and atmospheric composition in different ways, depending on where the cool, dense airmass originates.

In this study, we use the Regional Atmospheric Modeling System (RAMS) to assess the roles of such processes in events observed during the DOE ARM TRacking Aerosol Convection interactions ExpeRiment (TRACER) campaign. Specifically, we identify and simulate cases in which field observations suggest that interactions with cold pools and sea-breeze flows may have influenced convective evolution. Then, for each case, we conduct new simulations using a mechanism-denial approach that systematically suppresses sea-breeze and/or cold pool formation. Finally, we examine patterns of convective development across each event’s suite of simulations in order to assess storms’ separate and combined sensitivity to sea-breeze flows and cold pools.