Tropical cyclones, wildfires and regional precipitations are taken as examples of extreme weather. Their local and remote interactions with the environment and with each other are studied. Diabatic heating anomalies in both the atmosphere and ocean lead to large scale circulation anomalies, allowing for teleconnections of extreme weather events; while changing surface friction represents a kind of direct interaction with the environment.
Tropical cyclones in the Caribbean bring anomalous precipitation and hence latent heating and ascent over the region, resulting in a cross-equatorial thermally direct Hadley-type circulation anomaly with a descending branch over the Amazon and promotes fire-favourable atmospheric conditions there.
A new SubNiño4 index designed to capture the evolution of Pacific subsurface heat content in the El Niño-Southern Oscillation cycle is studied and shown to act as a long-range indicator for surface signals of the said cycle, outperforming the commonly used western equatorial Pacific warm water volume anomaly. It further works for atmospheric responses driven by the said cycle, including regional precipitation anomalies throughout the tropics and fires in Continental and Maritime Southeast Asia.
The boundary layer profiles of intensifying and steady-state tropical storms making landfall near Hong Kong are similar to each other but distinct from decaying ones. The decaying tropical storms have stronger inflow than non-decaying ones, driven by a much larger inflow angle in the mid- to low-level of the boundary layer under similar reduction in wind speed throughout. This is attributed to the weakening storms experiencing enhanced surface friction from land.
A sharp decrease in surface friction leads to the first, predominately purely dynamical, stage of a fast-slow re-intensification process in tropical cyclones moving back over ocean from land. They then continue onto a thermodynamically driven intensification due to a resumption of latent heat and moisture supply from a warm and moist ocean surface.