Irrigation affects the occurrence of heat waves globally, but its dynamics with local climate shifts and varying irrigation levels are not well understood. Utilizing observational data, spatiotemporal multivariate regression, and the window search algorithm, we delineate the effect of irrigation on heat waves in the North China Plain (NCP) before and after 1996. The results indicate that although the overall influence of irrigation is modest, contributing to a reduction of approximately 10 % in heat wave development, significant spatiotemporal heterogeneity is observed. Initially, irrigation mitigated northern and enhanced southern heat waves. Over time, the focus of mitigation expanded southwest, reducing the trend of heat wave frequency by 0.232 days/decade. We believe that local moisture conditions can explain these variations, which are visually represented through land-atmosphere coupling strength. Driven by climate mode shifts, overall aridity across the NCP has intensified, particularly in the southwest. The land-atmosphere coupling strength remains strong in the north but reverses in the southwest, leading to spatiotemporal heterogeneity of irrigation effects.

中文翻译：

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华北平原热浪灌溉的时空异质性

灌溉影响着全球热浪的发生，但其随当地气候变化和不同灌溉水平的动态变化尚不清楚。利用观测数据、时空多元回归和窗口搜索算法，我们描绘了 1996 年前后灌溉对华北平原 （NCP） 热浪的影响。结果表明，尽管灌溉的总体影响不大，有助于减少约 10% 的热浪发展，但观察到显着的时空异质性。最初，灌溉减轻了北部的热浪，并增强了南部的热浪。随着时间的推移，缓解的重点向西南方向扩展，使热浪频率的趋势降低了 0.232 天/十年。我们相信当地的水分条件可以解释这些变化，这些变化通过陆地-大气耦合强度直观地表示。在气候模式变化的推动下，整个 NCP 的整体干旱加剧，尤其是在西南部。北部陆地-大气耦合强度仍然很强，而西南地区则相反，导致灌溉效应的时空异质性。