Hot extremes in a warming climate  We have reported an elevated risk of island-wide heatwaves in Taiwan, and suggested that humid heatwaves in Taiwan can have higher mortality risks in future climate(Kueh et al. 2017). The associated circulation anomaly pattern, which reveals the dominance of western North Pacific subtropical high, and the relevant thermodynamic processes remain true for the future, suggesting a robust mechanism of island-wide heatwaves in Taiwan. In addition, we have related the weather conditions and local air quality during city-scale heatwaves in Taiwan (Kueh et al. 2018). In the northern and southern cities, high concentrations of ozone and PM2.5 were associated with different flow regimes. A further research on the preferential flows for city-scale heatwaves in Taiwan in a warming climate is ongoing. Moreover, we have studied the drivers and the extended range prediction of the 2018 summertime concurrent heatwaves occurred in the northwestern Europe and northeastern Asia. For the northwest European heatwaves, the successful prediction at longer lead time depends on the model's ability to capture the blocking and subtropical ridge (Kueh and Lin, 2020). The research on the drivers of concurrent Eurasian heatwaves in 2018 is ongoing.

Regional and local air-sea interaction in extra-tropics  In the extra-tropics, transient sub-synoptic to synoptic systems can exert large influences on the upper ocean variability. In most cases, ocean dynamics play a crucial role in the passive responses and re-stratification of the upper ocean upon the atmospheric forcing, thereby modulating the oceanic feedback on the atmosphere. By using a suite of observational data, our study indicated that springtime synoptic conditions control the local air-sea interaction processes related to boundary layer clouds in the Taiwan Strait (Kueh and Lin, 2014). We then studied the upper ocean response and feedback to a sequence of springtime weather events over the East China Sea based on the simulations from a regional ocean-atmosphere coupled model (Kueh and Lin, 2015.) We documented the variations in the oceanic mixed layer after the passages of a cold front and the ensuring cold-air outbreak, and highlighted the preconditioning of surface re-stratification on the development of a Taiwan low thereafter. This study offers implication in the role of model representation of upper ocean heat content in extended-range prediction.