The 2022 summer heat wave over China: An analysis of the severity and dominance from the frequency and intensity of high temperature

Abstract

AbstractSummer high temperature is an important climate issue. Severe heat waves occurred over China during summer 2022. Using daily temperature, we examine the severity of the 2022 high‐temperature event, and explore the dominance of summer cumulative temperature from the frequency and intensity of high temperature, for both the interannual variation of the 63 years (1960–2022) and the year of 2022. Corresponding to different “high” temperature thresholds, the frequency (number of the days) of high temperature, the summer cumulative temperature, and the intensity of high temperature are obtained for each summer with the daily data. Statistical tests show that cumulative temperature can be linearly regressed to frequency and intensity, which can help find the dominance from the two factors. For interannual variation, the comparison of the normalized regression coefficients suggests that, in the variation of cumulative temperature, the relative importance can vary from “dominated by intensity”, which corresponds to low temperature threshold (28°C), to “dominated by frequency”, which corresponds to high threshold (36°C). For the year 2022, we compare the two terms in the regression, which uses the coefficients from multi‐year regression along with the normalized frequency and intensity of this year, to determine the relative importance. Results show that overall it also varies from “dominated by intensity” to “dominated by frequency”, with the increase in threshold. Note that, for the two cases, these are the overall situation for the whole country; however, for each specific station, whether frequency or intensity dominates needs to be determined with the measures. A moderate threshold of 32°C, which considers both frequency and intensity, is suggested for practical applications.