Quantifying the influence of 2D and 3D urban morphology on the thermal environment across climatic zones

• Significant differences in surface regional heat island intensity between cities of different climate types. • 3D urban morphology effectively improve the interpretation of surface regional heat island intensity. • Trees have a more significant cooling effect than the rest of the green space types. • Green to gray facility area or volume ratio has cooling effect limitations. Urban heat islands (UHIs) exert a substantially negative impact on human health and urban sustainability. The role of two-dimensional (2D) landscape patterns in UHIs are well documented; while the effects and contributions of three-dimensional (3D) urban structures remain unclear, especially across different climatic zones. Here we investigated the relationship between 2D/3D urban morphology and the urban thermal environment in summer and winter during the day and at night in 62 representative large cities across four major climate zones in China. First, we extracted the seasonal surface regional heat island intensity (SRHII) using the MODIS 8-Day land surface temperature product. Subsequently, we constructed 25 2D and five 3D urban features and explored their relative importance and respective roles in UHIs in different climatic contexts. Results show that: (1) significant differences (p < 0.05) exist in SRHII between various climate zones; cities with a humid subtropical climate experience temperatures approximately 2 °C higher during the day in summer compared to those with the other climate types. (2) 3D urban features can effectively improve the interpretation of urban features for SRHII, with an average optimization level of 21%. (3) Urban trees have a higher cooling effect than other green spaces, whereas tall buildings can also reduce the UHI effect. (4) On summer days, equal proportions of tree to building volume provide the greatest cooling effects. This study provides new insights into the effect of 3D urban characteristics on SRHII and has promising implications for climate resilience planning and heat-related risk management