The Interaction between the Diurnal Cycle of Convection and Easterly Waves in Costa Rica: a Modeling Study

Easterly waves are important features of the tropical atmosphere, often serving as precursors to tropical cyclones, they are one of the main contributors to summer rainfall in Central America and are often associated with extreme rainfall events. Although they have been studied in several contexts, easterly waves still present us with many unanswered questions, particularly in how they interact with deep convection. Here, some of these questions will be addressed using high-resolution numerical simulations conducted using reanalysis data and centered on Costa Rica, whose weather is particularly affected by easterly waves. We will begin by validating the model simulations using a comparison with high-frequency radiosonde data acquired during the Organization of Tropical East Pacific Convection (OTREC) field campaign, which took place in Costa Rica and Colombia in 2019. We will then address the question of how easterly waves affect the characteristics of the diurnal cycle of convection and the degree of convective organization, the latter quantified using a convective organizational index. Finally, using a series of sensitivity experiments, we will discuss the role of surface moisture in modulating the interaction between easterly waves and the diurnal cycle of convection.