Compared with the likelihood of the HWMI between strong and weak WPSH in the ALL simulations, we find 32% [(95% CI: 31%-35%) for the HWMI; cf.
Given the strong WPSH, 23% [95% CI: 21 %-28% for the HWMI; cf.
CMIP5-based FAR analyses suggest that approximately 23% (95% CI: 21%-28%) of the risk of such events might be attributed to global warming and 32% (95% CI: 31%-35%) of the risk might be due to the WPSH. The urban heat island over the metropolis increases the likelihood of such events by 2.5 times and contributes 36% of severity of the 2017 extreme heatwave over the Yangtze River Delta.
(2014) reported 58% of attributable risk to global warming, which is near the sum (27% + 30% = 57%) of attributable risk to global warming and the WPSH in the 2017 extreme heat over the Yangtze River Delta.
We find that the FAR of such events over the Yangtze River Delta to the WPSH is relatively higher than that to global warming.
The HWMI categories are as folows: [less than or equal to] 1 normal <2 [less than or equal to] moderate <3 [less than or equal to] severe <4 [less than or equal to] extreme Stable lights from the defense meteorological satellite program are used to describe metropolis and rural regions, (b) Time series of the July-August mean west-extending ridge point position of the western Pacific subtropical high (WPSH) (in blue lines), and the July-August means of daily maximum air temperatures (in black lines) and the HWMI (in red lines) over Xujiahui station (from 1873), for urban and rural regions.