Title: Observing Atlantic Ocean Tropical Instability Waves: From multidecadal trends to frontal scale variability
Abstract:
In the equatorial Atlantic, intraseasonal variability in temperature, salinity, sea surface height, and current velocity is largely governed by the presence and propagation of Tropical Instability Waves (TIWs). These waves manifest as quasi-monthly, westward-propagating anomalies not only in physical ocean variables but also in biogeochemical parameters such as chlorophyll, oxygen, carbon and nutrients. Near the equator, lateral and vertical shear of the mean zonal currents generates barotropic and baroclinic instability that provide eddy kinetic energy for the formation of TIWs. Through advection and enhanced vertical mixing, TIWs redistribute heat and freshwater. By modulating sea surface temperature, TIWs can also influence the large-scale atmospheric circulation. More recently, TIWs and the free equatorial waves they excite have also been identified as an important component and maintenance mechanism of the deep equatorial Atlantic circulation.
In this seminar, I will present an overview of the current understanding of the seasonal cycle, interannual variability, and long-term trends of TIWs in the Atlantic Ocean, highlighting the observations that have been instrumental in advancing our knowledge. In the second part, I will focus on outstanding questions concerning the small-scale processes associated with TIW frontal dynamics from a multidisciplinary perspective. Finally, I will provide a first glimpse into ongoing field experiments and planned observational campaigns aimed at improving our understanding of key processes occurring at the sharp fronts of TIWs.
