Understanding the interaction between large-scale circulation and convection and how such feedback results in the synoptic and planetary scale organization of convection is a fundamental problem in tropical meteorology. It is assumed that the equatorial waves play a central role in such interactions by enabling momentum transport across different scales. In my research I focus on understanding the genesis and maintenance of equatorial waves and their coupling in convective and dynamical fields using observations, theory and hierarchy of numerical models and try to bring out its role in maintaining the large-scale circulation modes in the tropics. It is expected that a better understanding of the factors influencing the convection-circulation coupling would help in improving the representation of convective processes in climate models and will thereby help in improving the climate model simulations.
Our recent studies reveal that intrusion of extratropical air results in the genesis of tropical synoptic scale disturbances. We find that extratropical stratospheric air intrusion is an important factor in inducing low-level vortex seeds over the western north Pacific Ocean which in turn propagate northwestward and initiate low-pressure system over the Bay of Bengal. We also find that extratropical forcing plays a crucial role in the genesis of Mixed Rossby-Gravity waves, an important tropical synoptic scale mode of variability, during boreal winter season. We notice that the extratropical forcing is critical for increasing the intensity of the MRG waves during boreal summer. The results highlight the impact of extratropical dynamics on tropical modes of variability and emphasizing the importance of realistic represention of extratropical-tropical interactions in numerical weather prediction models.
Currently we are trying to physically explain the genesis of tropical synoptic scale disturbances caused by the intrusion of extratropical disturbances. We also focus on quantifying the role of large-scale convective activity in triggering the tropical synoptic scale disturbances.