Urban heat island (UHI) is human-induced temperature reflected on the earth's surface. Although spatiotemporal variations and driving factors of UHI have been explored extensively, the underlying mechanisms of UHI remain uncertain. Using multi-source datasets of air temperature (Ta) and surface heat flux variables, we quantify the dynamics of urban-rural Ta difference (ΔT) at monthly, seasonal and annual time scales for nine cities in Pearl River Delta (PRD) during 2000–2017. The impact of sensible heat flux and latent heat flux on UHI variations are further investigated from the perspective of the surface energy balance theory. Results demonstrate that all PRD cities have apparent UHI, as evidenced by maximum ΔT in summer and minimum ΔT in winter. A notably declining trend of ΔT is observed in Shenzhen and Guangzhou, which have the largest population and build-up areas, during 2000–2017. However, trends of ΔT are not statistically significant in other cities. Attribution analysis reveals that sensible heat and latent heat significantly affect the UHI at different stages of urbanization. For the nine cities in PRD, the primary factor responsible for heat convection is the varied urban compositions formed by different developing trajectories. Specifically, sensible heat flux contributes substantially to ΔT changes in Dongguan and Shenzhen, which experienced rapid urban expansion and with complex urban structures. By contrast, latent heat flux dominates the ΔT changes in Zhongshan and Huizhou where relatively simple urban structures are preserved. Our study highlights the importance of urban patterns, sensible heat, and latent heat to understand the UHI dynamics and variations in PRD, which provides guidance for developing appropriate mitigation strategies in city planning to alleviate UHI-related burdens.

城市热岛（UHI）是人为引起的温度，反射到地球表面。尽管已经广泛地探索了UHI的时空变化和驱动因素，但是UHI的潜在机制仍然不确定。利用空气温度（Ta）和地表热通量变量的多源数据集，我们对2000年珠江三角洲（PRD）九个城市在月度，季节和年度时间尺度上的城乡Ta差异（ΔT）进行了定量分析–2017年。从表面能平衡理论的角度，进一步研究了显热通量和潜热通量对UHI变化的影响。结果表明，珠三角所有城市都有明显的超高吸水率，夏季最大ΔT和冬季最小ΔT证明了这一点。在深圳和广州，ΔT呈明显下降趋势，在2000–2017年期间，这些国家的人口和建筑面积最大。但是，在其他城市，ΔT的趋势在统计上并不显着。归因分析显示，在城市化的不同阶段，显热和潜热显着影响超高热。对于珠三角的9个城市，造成热对流的主要因素是由不同的发展轨迹形成的变化的城市组成。具体来说，感热通量在东莞和深圳经历了快速的城市扩张和复杂的城市结构，对ΔT的变化起了很大作用。相比之下，在保留相对简单的城市结构的中山和惠州，潜热通量主导着ΔT的变化。我们的研究强调了城市格局，显热，