Table 4.

Temperature zone classification Method.

Temperature Zone Level	Classification Method
High Temperature Zone	> +
Sub-high Temperature Zone	+ 0.5 < ≤ +
Middle Temperature Zone	− 0.5 ≤ ≤ + 0.5
Sub-middle Temperature Zone	− ≤ < − 0.5
Low Temperature Zone	< −

Note: Ts represents temperature, µ is the mean temperature, and std is the standard deviation of temperature. In addition to the five thermal zones, the surface heat island imbalance index (SHII) was calculated to quantify the net imbalance of the urban thermal field: