Objective High temperature weather is one of the most important meteorological factors that closely bound with the electricity supplies and loads.

Methed  Applying the regional heat process (RHP) characterization standard and the comprehensive intensity assessment model, the RHPs were identified and characterized in Southern China and its four units, i.e., Central unit (CU), Eastern unit (EU), Southern unit (SU) and Western unit (WU). The heat period length, frequency and duration, average temperature and maximum temperature, extent and comprehensive intensity were objectively analyzed and compared.

Result It is found that: (1) In recent six decades, Southern China and its four units (i.e., CU, EU, SU, WU) have taken place a total of 70, 197, 139, 225, and 48 times of RHPs respectively; the yearly average of heat days are 16.2, 22.9, 17.7, 18.2, and 8.1 days; the heat period last 26.1, 51.3, 37.3, 53.1 and 16.4 days on annual average. Based on frequency, duration, heat period length, extreme temperature, and comprehensive intensity, CU and SU tend to be more easily influenced by RHPs than other two units. (2) The trend analysis suggests that most parts of Southern China share a significant delaying feature of the ending and a significant lengthening of the heat period; meanwhile, the frequency, cumulative duration and maximum extent also show an increasing trend; Only CU and SU show a significant earlier beginning of RHPs . (3) Following the Sequential Mann-Kendall tests, an abrupt speeding is often detected in 1970s and 1980s for the delaying of the ending, the prolonging of the heat period and the increasing of the cumulative duration. Once the abrupt change happened, the corresponding linear trend after the change point will get more violent. (4) RHPs influence the eletricity supply and deamand balance, when RHPs happen, units depending on outside electricity supplies would have bigger demands while units capable of transfering electricity outside would face an augmentation in its electrical consumption.

Conclution  Overall, the heat wave disaster in Souterhn China tends to be heavier in a way of prolonging heat period, uprising frequency, amplifying extent, and aggravating comprehensive intensity, which bring stronger challenges to the electricity dispatch and power generation. The overall severity of four units can be listed as CU, EU, SU and WU following a decreasing order.