Interdecadal Variation of Springtime Compound Temperature-Precipitation Extreme Events in China and its Association with Atlantic Multidecadal Oscillation and Interdecadal Pacific Oscillation

The concurrent occurrence of temperature and precipitation extremes, known as compound temperature-precipitation extreme events (CTPEEs), leads to more pronounced consequences for human society and ecosystems than when these extremes occur separately. However, such compound extremes have not been sufficiently studied, especially during boreal spring. Spring is an important transition season, during which the CTPEEs plays a pivotal role in plant growth and revival of terrestrial ecosystems. This study investigates the spatio-temporal variation characteristics of spring CTPEEs in China, including warm-dry, warm-wet, cold-dry and cold-wet combinations. The compound cold-wet extreme events occur most frequently, followed by warm-dry, warm-wet and cold-dry events. The frequency of CTPEEs associated with warm (cold) extremes shows a marked interdecadal increase (decrease) since the mid-to-late 1990s. It is found that the interdecadal change in CTPEEs is primarily determined by the variation in temperature extremes. This interdecadal shift coincides with the phase transitions of the Atlantic Multidecadal Oscillation (AMO) and the Interdecadal Pacific Oscillation (IPO). After the mid-to-late 1990s, the configuration of a positive AMO and a negative IPO excited atmospheric wave trains over mid-high latitudes, causing high-pressure and anticyclonic anomalies over East Asia. This leads to less cloudiness, allowing an increase in downward solar radiation, which enhances surface warming and contributes to an increase (decrease) in warm-dry and warm-wet extremes. The above observations are confirmed by the Pacemaker experiments. The results of this study highlight a significant contribution of internal climate variability to interdecadal changes in CTPEEs at the regional scale.