Abstract Heat waves are unusually high temperature events over consecutive days and may cause adverse impacts such as morbidity and mortality. The interaction between heat waves and urban heat island (UHI) effects has remained a subject of debate, as some studies prove heat wave-UHI synergy while others do not. Furthermore, heat waves affect tropical cities more severely than mid-latitude cities, but there is a disproportionate lack of heat wave studies focusing on tropical cities. We attempt to narrow this gap by studying the heat wave in Singapore in April 2016 using ground observations and the Weather Research and Forecasting (WRF) model. Compared to non-heat wave days, the ground observations show that daytime temperatures can be 3 °C higher during the heat wave. Despite the temperature spike, the UHI intensity is not amplified during the heat wave, maintaining its peak near 2.5 °C during both heat wave and non-heat wave periods. WRF simulation results also agree well with measurements and predict UHI peaks near 2.5 °C during both periods, showing no heat wave-UHI synergy. The spatially averaged UHI intensity also shows no such synergy. There is no significant change of wind speed, soil moisture availability or heat storage flux during the heat wave. Therefore, the lack of heat wave-UHI synergy in our study is consistent with current understanding of factors contributing to UHI. This study shows that the heat wave-UHI interaction in a tropical city can be different from that in cities in the temperate climate zone and more studies should be conducted in tropical cities, which are projected to suffer larger impacts of increasing heat stress.

中文翻译：

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热浪与城市热岛的相互作用：以新加坡热带沿海城市为例

摘要 热浪是连续几天发生的异常高温事件，可能导致发病率和死亡率等不利影响。热浪和城市热岛 (UHI) 效应之间的相互作用仍然是一个有争议的话题，因为一些研究证明了热浪与 UHI 的协同作用，而另一些则没有。此外，热浪对热带城市的影响比中纬度城市更严重，但以热带城市为重点的热浪研究严重缺乏。我们试图通过使用地面观测和天气研究与预测 (WRF) 模型研究 2016 年 4 月新加坡的热浪来缩小这一差距。与非热浪日相比，地面观测表明，热浪期间白天的温度可能会高出 3°C。尽管气温飙升，UHI 强度在热浪期间不会放大，在热浪和非热浪期间均保持在 2.5 °C 附近的峰值。WRF 模拟结果也与测量结果非常吻合，并预测两个时期内 UHI 峰值接近 2.5 °C，表明没有热浪-UHI 协同作用。空间平均的 UHI 强度也没有显示出这种协同作用。热浪期间风速、土壤水分有效性或蓄热通量没有显着变化。因此，我们研究中缺乏热浪-UHI 协同作用与目前对 UHI 影响因素的理解是一致的。这项研究表明，热带城市的热浪-UHI 相互作用可能与温带气候区的城市不同，应在热带城市进行更多研究，