Concentric Gravity Waves: A study of Secondary Waves over Brazil

Abstract

Secondary concentric gravity waves (CGWs) are atmospheric gravity waves (GWs) generated due to the dissipation/breaking of primary gravity waves. Primary GWs, on the other hand, are gravity waves generated in the troposphere and are related to meteorological activities (like deep convection), orographic forcing, and wind shear. Propagating primary waves transport their energy and momentum to the upper atmosphere. As the primary GWs give off their energy/momentum to the background atmosphere through dissipation, they create body forces that decelerate or accelerate the mean flow. As a result, secondary GWs with concentric wavefronts are generated and in turn transport the transferred momentum/energy to other levels of the atmosphere. These multistep vertical coupling mechanism has been reported in literature as the underlying mechanisms for the generation of other phenomena such as traveling ionospheric disturbances and equatorial plasma bubbles. Since secondary CGWs have been known to indicate these multistep vertical coupling processes through observation and simulation, a detailed understanding is needed to directly relate these multistep generated phenomena to their primary source. Therefore, this postdoctoral proposal aims to investigate the vertical coupling of the atmosphere using observations and simulations of secondary CGWs over the Brazilian sector. In this work, ground-based all-sky imagers and space-borne instruments: Atmospheric Infrared Sounder (AIRS), and Visible Infrared Imaging Radiometer (VIIRS) will be used to observe and investigate CGWs. Then, the waves will be classified as primary or secondary depending on the sources determined using a ray tracing model. Furthermore, a numerical model following an existing and operational general circulation model (GCM) will be developed to study in detail the generation, propagation, and dissipation of the identified primary and secondary CGWs.