| Deep convection is a key aspect of the tropical atmosphere. Local factors control its existence and strength, and these factors are in turn affected by large-scale processes. One example is found in the eastern tropical Pacific, where observations have suggested a link between deep convection and stratospheric intrusions into the tropical upper troposphere. Here we perform an analysis of the connection between these stratospheric intrusions and convection in this region, using a combination of data analysis, potential vorticity (PV) inversion diagnostics, and numerical simulations.; First a climatological study of intrusions with respect to its three-dimensional structure and accompanying outgoing longwave radiation (used as proxy for convection) is performed. This analysis shows that intrusion events have remarkably similar evolution and structure, and that transient convection nearly always occurs at the leading edge of the PV tongue. This confirms previous studies that have shown a close link between Rossby wave activity and transient convection.; PV inversion is then used to quantitatively assess the contribution of the upper level PV anomaly associated with the intrusion to changes in the dynamical and thermodynamical structure of the atmosphere. This establishes a formal link between the PV anomaly and quantities that characterize convection (convective available potential energy CAPE, vertical velocity, static stability). We verified that there is lower static stability and upward vertical motion at or around the leading edge of the intrusion, coincident with the area of convection and of positive advection of PV, and consistent with proposed theory. Moreover, we determined that the upper-level PV intrusion has the dominant contribution to promote atmospheric destabilization, CAPE build-up and vertical velocity.; Finally, numerical model simulation are used to corroborate the above results (mechanisms), and also to examine the role of convection in the evolution of the PV anomaly. These simulations confirm that the PV intrusion is a key element for convection to occur. Also, analysis of simulations showed that here is a qualitatively good agreement with results from PV inversion diagnostics. Simulation results also show that the diabatic source of PV due to latent heat release plays a significant role in determining the shape of the intrusion. |
