The tropical influence to the extratropics is significant. A classic example is the global influence of ENSO. See a blog post by Prof. Issac Held that explains this clearly. Once established, the stationary wave pattern triggered by anomalous convection does not vary much as time involves.

The influence of extratropics on the tropics, on the other hand, involves various distinct stages. Many theories have been proposed to explain the equilibrium responses to forcings or the statistical relationship between the extratropical and tropical climate. There are, however, gaps between theories, modeling simulations, and observational data. Using a model hierarchy, we seek a systematic understanding of processes with different timescales: atmospheric dynamics (inter-seasonal), air-sea flux (inter-annual), and ocean circulation adjustments (decadal).

Click here for our papers investigating the characteristics and the mechanisms of each process.

A lot of progress has been made via understanding the internal variabilities of our climate system (e.g. ENSO and annular mode). To the first order, these various modes of variabilities arise from the atmospheric and oceanic waves or the interaction between them.

Anthropogenic climate change, on the other hand, originates from changes in energy (including the greenhouse effect of CO2 and the aerosol indirect effect). The radiative feedbacks, the ocean heat uptake, and their interactions with atmospheric dynamics appear to hold the key for tackling the problem.

Please see here for our attempts to understand the role of clouds and ocean in shaping the patterns of climate change.