Decadal trends analysis of extreme high temperatures and case simulation assessment in summer over Eastern China

This is the authors' abstract. We don't add key points for this paper.

Using the daily maximum temperature from the 0.5° × 0.5° grid datasets (V2.0) covering China during 1961–2020, this study conducts a decadal-scale spatio-temporal analysis of summer daily maximum temperatures across eastern China (east of 110°E, excluding Inner Mongolia and Northeast China). The results indicate that daily maximum temperatures during the summer months (June–August) exhibited a significant warming trend across three statistical measures—minimum, mean, and maximum values. The minimum temperature showed the most pronounced increase, rising by over 2 °C in the past six decades and accompanied by a broader temperature distribution. This trend was especially evident in central and eastern regions, indicating a marked intensification in both the frequency and severity of extreme heat events. Additionally, the study evaluated the performance of four operational forecasting models—CMA, ECMWF, NCEP, and UKMO—which participate in the Subseasonal to Seasonal (S2S) Prediction Project. The assessment found that short-term forecasts (1–10 days) had relatively small biases and high accuracy. UKMO is more reliable for short-term applications, while ECMWF shows greater potential for extended-range forecasting. In terms of heatwave prediction, all four models performed well at the 5-day lead time, with CMA producing the most accurate forecasts.