华南复合型热浪的次季节可预测性研究

在气候变暖背景下，极端高温事件频发，影响不断扩大，对其的准确预测显得十分迫切。次季节预测能够弥合天气预报和季节性气候预测之间的缺口，是提高极端高温事件业务预测的关键所在。复合型热浪作为极端高温事件类型之一，相比于以往普遍关注的日间热浪，在我国华南表现出更为明显的上升趋势。然而，目前对华南复合型热浪及其次季节预测缺乏深入认识。另一方面，热带季节内振荡能够显著影响华南天气和气候，但是其能否影响华南复合型热浪及其次季节预测，如何影响，尚不清楚。因此，本项目将利用多源观测、再分析资料，结合先进的多模式回顾预报资料，系统性地分析华南复合型热浪的发生、发展、消亡等变化特征，重点揭示气候模式对华南复合型热浪的次季节预测能力，以及不同热带季节内振荡系统对华南复合型热浪及其次季节预测的影响，阐明其中物理机制。项目的开展可深化对华南复合型热浪的变化机理和次季节可预测性的认识，为改善区域热浪预报提供理论支撑。

Under the background of global warming, extreme heat events occur frequently around the world, and their impacts continue to expand, resulting in a growing demand for skillful predictions of extreme heat events. Sub-seasonal prediction can bridge the gap between short-term weather forecasting and long-term climate prediction, and is the key for improving operational forecasts of extreme heat events. As one of the heat extreme types, compound heat wave occurrence in terms of magnitude and frequency, has experienced a more obvious increasing trend over South China, compared to daytime heat wave that has been generally concerned in the previous studies. However, there is a lack of comprehensive understanding of South China compound heat wave and its sub-seasonal prediction. Furthermore, intraseasonal oscillations exert significant influences on weather and climate over South China. Whether the intraseasonal oscillations can affect variations and predictions of the South China compound heat waves, and how, are remain unclear. This proposal will use in-situ observations, reanalysis datasets, and hindcast datasets from state-of-the-art climate models, to analyze the evolutional characteristics of compound heat waves over South China and to what extent it can be reproduced by the climate models on sub-seasonal scale. In particular, this proposed study tends to reveal roles of different intraseasonal oscillations on South China compound heat waves and their sub-seasonal predictions, as well as the underlying mechanisms. A comprehensive understanding of the associated mechanisms and sub-seasonal predictability of South China compound heat waves from this proposed study could provide a theoretical basis for improving the prediction of regional heat waves.