Investigating the interactional synergies between urban overheating (UO) and synoptic scale weather patterns during heatwaves in a coastal city

Heatwaves' frequency and intensity have increased over time. The potential synergy between local-scale urban overheating (UO) and global weather patterns could have severe consequences for climatic conditions at the local, regional, and global levels. The relationship between atmospheric variables and UO has been the subject of considerable investigation. However, the correlation between UO and global-scale weather patterns, particularly in the context of heatwaves, has yet to be extensively investigated. The present work used the recently developed gridded weather type classification (GWTC) to investigate the influence of global-scale weather patterns (WPs) on UO during heatwaves in a coastal city (Sydney). The impact of humid warm (HW) and warm (W) weather patterns (WPs) was found to be more significant during heatwaves, with both WPs transpiring over 76% of the time and increasing the mean UO magnitude by 6 to 9°C in western Sydney and 3.8 to 5.4°C in inner Sydney. Dry (D) and seasonal (S) WPs predominated during non-heatwave (background), with mean UO magnitudes varying from 2.4 to 4.0°C in western Sydney and 0.6 to 1.0°C in inner Sydney. The weather patterns HW and W indicates dualistic synoptic systems situated on the contrasting sides of the metropolis. Based on the findings of this study, appropriate adaptation and mitigation solutions for extreme heat conditions can be developed.