2-Day Westward-Propagating Inertio-Gravity Waves during GOAmazon

Abstract:

Rainfall over tropical South America is known to be modulated by convectively-coupled waves such as the convectively coupled Westward Inertio-Gravity Waves (WIGs). In this work, the origin and dynamical features of South American WIGs are analyzed using 8-times daily satellite-observed brightness temperature, and 2014-15 Observations and Modeling of the Green Ocean Amazon (GOAmazon) field campaign over the Central Amazon.

Statistical analyses reveal that 2-day these disturbances propagate westward over Amazonian at about 24-27 m s^-1 and is more active during the South America rainy seasons (November-May), with a peak in April. Results also suggest that squall lines over the Amazon in many instances are organized in 2-day disturbances. Sounding-based thermodynamic budgets and cloud profiles reveal cloud life cycle of 2-day convective disturbances evolve: from shallow, followed by cumulus congestus, deep convection during the active phase, and finally stratiform precipitation. Boundary layer conditions, on the other hand, play important role in determining important features of 2-day convection. To advance our understanding on the relationship between precipitation and WIGs, a recently-developed buoyancy-based approach is also presented. Results show that buoyancy-based is a better predictor of convection for 2-day disturbance over the Amazon than the often-used moist static energy (MSE).