Spatiotemporal Dynamics and Drivers of Daytime and Nighttime Urban Heat Islands in the Guangdong-Hong Kong-Macao Greater Bay Area: Insights from XGBoost-SHAP

DOI: 10.22161/ijeab.113.19

Abstract:
The Guangdong-Hong Kong-Macao Greater Bay Area (GBA) is a representative region in China characterized by a high level of urbanization, rapid land-use changes, and intensive population and economic activities. Identifying the spatiotemporal patterns and driving factors of daytime and nighttime surface urban heat island (SUHI) intensity is of great significance for regional thermal environment management and territorial spatial planning. Based on multi-source datasets from 2018 to 2024, this study developed an analytical framework consisting of “SUHI pattern identification–land-use transition response–driving mechanism interpretation” to reveal the evolution and driving mechanisms of the thermal environment in the GBA from a diurnal perspective. The results showed that: (1) High SUHI values during both daytime and nighttime were concentrated in core built-up areas such as Guangzhou, Foshan, Dongguan, and Shenzhen, whereas low-value areas were mainly distributed in mountainous forest regions in the north and coastal water bodies along the Pearl River Estuary. (2) From 2018 to 2024, SUHI intensity exhibited overall fluctuations, with an increasing trend in the eastern urban corridor of the Pearl River Delta, whereas the northwestern mountainous areas remained relatively stable or experienced a slight decline. (3) The conversion of forestland, cropland, and water bodies/wetlands to construction land significantly intensified SUHI, with the strongest warming effect observed when water bodies/wetlands were converted to construction land. Conversely, the transformation of construction land into green spaces or water bodies effectively mitigated SUHI. (4) XGBoost-SHAP analysis revealed that NDBSI, NDVI, NDMI, MNDWI, and NTL were the key factors influencing daytime SUHI, whereas NDBSI, NTL, PD (population density), GDP, and NDVI were the primary drivers of nighttime SUHI. These findings provide a scientific basis for thermal environment regulation, urban expansion control, and blue-green space conservation in the GBA.

Keywords:
Guangdong-Hong Kong-Macao Greater Bay Area (GBA); Surface Urban Heat Island (SUHI); Daytime and Nighttime Differences; Land-use Transition; XGBoost-SHAP Model

Article Info:
Received: 16 May 2026; Received in revised form: 14 Jun 2026; Accepted: 17 Jun 2026; Available online: 24 Jun 2026

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